the european union and united kingdom have reached a post—brexit trade deal. it follows months of tough and often fraught negotiations. both sides have described the treaty as a success. much of the fine detail of what was agreed is still to be made public. the european commission president ursula von der leyen hailed it as a "good, fair and balanced deal". borisjohnson said the uk had "completed the biggest trade deal yet". the treaty is set to come into force in january and replaces the transition phase. a covid stimulus package, designed to revive the us economy has struggled to make progress in congress. the package is work over a $900 billion. republicans blocked an attempt to increase direct payments to individuals as demanded by president trump. so what's the reaction

to the deal been across the uk? we'll be hearing from our scotland correspondent james cook in glasgow, our wales correspondent tomos morgan in cardiff, but first here's our ireland correspondent emma vardy. just think back, the brexit process was so seismic for the island of ireland, because it threw up all of those questions over what to do about the irish land border and it reminded everyone of the troubled history of this place. but now many of the issues which once seemed unresolvable, there are now agreements on. and northern ireland enters this new era where doing trade here will be different from the rest of the uk, those special arrangements in order to keep that irish land border invisible. now, the trade deal has been welcomed here, it is likely to make some of those special arrangements for northern ireland easier to carry out in future and it will bring great relief in the irish republic, where many people's livelihoods, particularly in the food industry, depended on there being a deal for the future of trade between our two islands.

well, most of the reaction in scotland so far has focused on fish and chips — or, to be precise, seed potatoes. that's the type that farmers grow, not the type that you and i will hopefully roast tomorrow. this deal appears to prohibit their export from great britain into northern ireland or the european union. scottish farmers say that's a blow, although they say that avoiding a no—deal has been good news. the first minister of scotland says that the deal is disastrous and that brexit itself is disastrous. the prime minister, though, when it comes to fishing, insists that this is a great deal. now, many people in scotland's coastal communities voted for brexit because they thought it would mean taking back control of their waters. if they feel that hasn't happened, though, this could damage the conservatives here. and overall, this isn't just about food, it's not just about trade, it's about politics. a significant percentage of people in scotland, a big majority, voted against brexit — and there's no doubt that it's breathed life into the campaign

for independence. "any deal was better than no—deal, but this will still be a difficult deal for wales, a thin deal, and not the deal we were promised." those were the words of the first minister, mark drakeford, in response to this afternoon's announcement. now, one of the reasons it was so important that wales and the uk got this trade deal was because a higher percentage of wales‘s exports goes to the eu compared to the uk average, 10% more. and when it comes to things like welsh lamb and fish, they top around 90% going to countries within the eu. the first minister has written to the presiding officer, calling for the welsh parliament to be recalled next week so they can scrutinise this new trade deal. that will hopefully be done around wednesday, so even though there is some concern around the specifics of this deal, it's still a better deal, mark drakeford said,

than the no—deal scenario. now on bbc news, amanda ruggeri meets those developing new technologies to protect an ancient sunken city in italy. the roman settlement of baiae was the las vegas of the roman empire — a place where the rich and powerful came to relax, party and carry out illicit affairs. lured by baiae's volcanic hot springs, the romans built opulent villas and baths here on the gulf of naples. today, it is still famed for its precious marbles, mosaics and sculptures. the ancient authors wrote a lot about baiae and described baiae as a little rome — as a place for the holiday,

a place grounded with all the aristocracy, but also with young people, with people walking on the beach, looking to the sea, people drinking wine. a fun atmosphere. it sounds like a party town. exactly. laughter. but over several centuries the city slowly sunk beneath the sea. burning. this area? more dangerous than. . .there. i wish you told me that when we were over there. why are you telling me that when we're here? the underwater site is a treasure trove of mosaics and marbles dating back 2,000 years. but today they are at risk. now a team of archaeologists and engineers are developing some surprising new technologies to protect the underwater site forfuture generations.

we know baiae as the underwater city. baiae is not an underwater city, it is kilometres of the ancient waterfront that is now underwater because of a sudden change of the sea level. you can see underwater the remains of actual the villas, also the remains of marbles, streets, shops. is there anything else like that in the world? i don't think that you can find other underwater archaeological sites in the world like baiae. baiae, on the gulf of naples, is one of the most extraordinary ancient sites in italy. the romans came here for the same reasons we do — the sparkling mediterranean, the balmy weather, the lush vegetation and vineyards. they were also drawn to the area's thermal springs — the result of course, of the volcanic activity beneath their feet.

as the roman republic lapsed into empire, baiae's reputation only grew. in ad 39, caligula built a bridge made up of merchant ships linked together and then covered with earth from baiae to nearby pozzuoli — three miles long — and rode over it in a chariot. and in ad 59, nero had his mother, agrippina, murdered in her villa here. the later emperor hadrian would have a more peaceful end to his life, dying of natural causes in his baiae palace in ad 138. university of naples "l'0rientale" archaeologist michele stefanile showed me around. baiae was a luxury resort with incredible architectures connected with the most eminent men of the late republic and the early imperial times.

the ancient authors wrote a lot about baiae and they described baiae as a rome — as a place for the holiday, a place crowded with all the aristocracy, but also the young people, with people walking on the beach and looking to the sea, people drinking wine. a fun atmosphere, it sounds like a party town. exactly. people like seneca, for example, decided to have his villa not in baiae but on a hill in that direction. just to stay a little bit isolated for the... it was too loud for him? exactly. too crazy for seneca. exactly. and when did this whole area disappear? we know that after the late antiquity, this part of the territory, of the phlegraean region was abandoned. so, how much to the water level rise? it depends on the part of baiae, but normally it's somewhere between four and six metres.

wow. it's a big change. it's a big one. yes, a very big change. that's why you can see underwater, not only the floors, but also walls. it's one of the sites in the world with this concentration of mosaics from the roman times, underwater. so, you can ride on the water and read a mystery five centuries long or six centuries long. so, tell me what happened. how did it get submerged? the history of the change of the sea level in this territory is connected with the volcanic activity. most of us have heard of mount vesuvius, but it turns out there's another volcanic zone near naples. it's burning. it's more dangerous than...there. i wish you told me that when we were over there! why are you telling me that when we're here? this area — called campi flegrei, or the phlegraean fields — is still active. it's also why baiae

is now underwater. the movement of magma underground actually sank the ancient city's ground level.

campi flegrei is one of the 20 known supervolcanoes on the planet, capable of erupting with a volume of thousands of times stronger than an average volcano.

vincenzo tells me that if it were to blow at maximum capacity today, it would make the ad 79 eruption of mount vesuvius — that destroyed pompeii — look like a puppy's sneeze.

carmine minopoli is a researcher at the national institute of geophysics

and volcanology. he walked me through how the monitoring system works, but before he did, we spoke in one of the stranger places i've ever done an interview — inside a building that had been abandoned because of the heat and gases caused by the volcanic vents beneath it.

all of that volcanic activity remains a risk today. but it's also what put baiae underwater 1,500 years ago. the water has helped preserve the artefacts, but it can also damage them. barbara davidde, director of the unit of underwater archaeology at italy's high institute for conservation and restoration, has been working at baiae since 1993. so, 1,500 years these artefact have been underwater. what does the sea water do to artefacts over such a long period of time? archaeological remains were protected underwater, thanks to the sea.

but if they are on the seabed, open, so not covered by the sand, they are attacked by marine organisms. we call bioerosion. there are sponges and bacteria, also bivalve animals, organisms, so there is a big variety of bioerosion. some statues that are recovered from the sea are completely destroyed or partially destroyed or sometimes we found that the neck, the head, the hand, is lost. and all the portion of the statues that are covered by sand are in good condition. concerning the mosaics for example, we can see some small holes that don't look so dangerous for the artefacts, but if we analyse with a microscope these holes, we will see that inside the tessera, inside the stone, the hole is not small

but it's big, large. and the monitoring of the site is the solution of this. at the archaeological museum of campi flegrei, one piece of artwork after another shows the damage animals can do. while it's common to see ancient roman statues missing arms or heads, the items in this collection are different. a veiled woman has been covered with what almost look like pockmarks. a base with a dedication to emperor hadrian loses all shape at the top, like a half—melted candle. this 71mm statue of zeus on his throne dating to the first century bc is covered with what looks like white scrawlings — the remnants of marine and crustaceans.

but these organisms weren't his only challenge. the zeus was likely stolen from the sea by looters. he wound up in the collection of thej paul getty museum in los angeles, acquired by a curator later indicted for conspiracy to traffic in illegal antiquities. he was returned to the campi flegrei museum in 2018. the other sculptures in the museum are now safe from marine organisms. but the artefacts that remain below the sea, including the precious floors that make up the largest collection of underwater roman mosaics in the world, remain at risk. finally, it was time for me to go down and see it for myself. i was invited to join the team testing new technologies to help better monitor the erosion, but also to help

the public engage with the site in new ways. chiara petrioli is professor of computer science at the university of rome "la sapienza", and the interdisciplinary project musas‘ site coordinator. she is behind one of the more ambitious aspects of musas — its underwater wireless sensor networks. so, what are the technologies you're testing here this week? this week, we are testing underwater drones supporting archaeologists in discovering the site. we are testing underwater wireless sensor networks that allow to gather in real—time, data on the conservation status of the site. the water quality, the c02, because here we have very active volcanic activity

and it's important to know what's happening there. and also images that we can transmit in real—time, compressed through novel algorithms from the underwater environment. these innovations represent a major change from how things were done in the past. they mean that information and pictures about any problems in the site, like erosion or even looting, can be communicated much more quickly. not only can underwater archaeologists communicate while they are diving, but we can get data in real—time about the site, even when archaeologists aren't there. so, we have also developed a system for divers. 0n the other hand, we are able to localise and we have developed a way to represent how these underwater cultural heritage sites were in the past using virtual reality, so that you can actually have an enhanced experience visiting the site. and you can also track

in a whatsapp—like matter with the rest of the divers and with your beloved ones on the other side of the planet, and exchange images or exchange your feelings, even when you are diving. the way this is being done is through an underwater internet. that's more difficult than it sounds. wi—fi, for example, doesn't travel far underwater. instead, petrioli's team came up with the idea of using acoustics inspired by marine mammals. so, you have to use a completely different way of communicating, for very short range, a few metres, which is short—range in this environment, you can use wireless optical. but mostly you have to use the way of communicating of marine mammals. so, you need to use acoustic communication. and this is really challenging because the sea parameters may change. the temperature and salinity change. and this affects the way communication works. and it's also, you know, a ship passing by, like, we have right now or water motorbike, this affects the ability to communicate.

even the wind rising so that the surface provides changes, affects the communication, then two devices are no longer able to communicate. so, it's very complex, but we came up with an idea. let's have mesh networks, like, multi—networks, and let's use artificial intelligence techniques to keep changing. the product we use, the route the information flow has to go through, the parameters of our communication system. and we came up with some novel fundamental understanding, and it works. what was not possible before is now possible in terms of performance, transmitting even multimedia information like images, in terms of real ability of communicating. and this is a gorgeous application in underwater cultural heritage, but this is going to change actually whatever we are able to do in terms of exploring

and understanding these environments across the blue economy. under the water, a whole world opens up. the sculptures here are replicas. the real ones are safe above ground in the nearby archaeological museum. but the other artefacts, from the walls to mosaics, are original. as we swam, statues began to appear out of the water. this was the nymphaeum of emperor claudius, a place where the first century ruler would have strolled and admired his sculptures. i pressed a button on my tablet and held it up. a 3d version of how the nymphaeum would've looked appeared on screen. this is one of the other main goals of musas — to help divers understand

and appreciate the ruins they're looking at. but the best was yet to come. my dive guide, enzo maione, stopped on the sea floor and started to push the sand around. with each sweep of his hand, more of the mosaic revealed itself until we were hovering over an intricate pattern of circles and hexagons. this was once the floor of a room just off the atrium of a magnificent villa dating to the second century. there's nothing quite like seeing ancient ruins like this. for one thing, there's the eerie silence of being underwater — hearing only your own breathing. for another, there's the intimacy. forget the crowds at sites like the colosseum, down here, where only scuba divers can go, you can experience this ancient landscape almost alone.

and knowing that it's being protected for future generations couldn't be a better feeling. the team installed the monitoring system at baiae permanently in summer 2020. the project is also being unrolled elsewhere, including at an ancient underwater site in puglia. it's a privilege to see it all in person and to learn how these innovations could dramatically improve the way the site is preserved by archaeologists and experienced by travellers.

hello. the weather is giving us a calm and mostly dry interlude for christmas day, a very chilly start with a touch of frost in places, but a fine day for the most part, with some spells of sunshine. where we have had some showers, particularly across eastern scotland and eastern england, there is the potentialfor some ice on untreated surfaces through the first part of the morning.

certainly a chilly start, with temperatures well below freezing, so a frost in many places, but that means a fine and a sunny start for most. still, some of the showers just draped across the eastern side of england, a fairly brisk wind here, and one or two showers, too, for parts of pembrokeshire and the west of cornwall. but for much of england and wales, we will see some spells of sunshine through the day. just a bit more cloud into the north west later. certainly for northern ireland and scotland, things will be clouding over, and we'll see some rain into western scotland. the winds strengthening here. but that's where we will see the highest temperatures. 9 degrees in stornoway. pretty chilly day elsewhere. and then as we head through christmas day night, into the early hours of boxing day, you can see generally more in the way of cloud. some outbreaks of rain, more of a breeze, so not such a cold start to the day on boxing day, most places well above freezing. but boxing day will generally be a cloudier day. there will be some bits and pieces of rain around and some quite heavy and persistent rain getting going across parts of western scotland, into northern ireland later as well, the winds really starting to pick up here.

it is going to be a milder day for most, but this will be taking us into actually quite a rough spell of weather through saturday night. it comes courtesy of this area of low pressure. it has been named by the met office, it has been named storm bella. it is going some really heavy rain, which could cause some flooding but also some really strong winds. a met office amber warning is in force already for parts of southern england and south wales, gusts of 70 to possibly 80 miles an hour, but more generally across england, wales and the far south of scotland, we'll see wind gusts of 60 miles an hour in many spots. a lot of rain through saturday night into the early part of sunday morning. that could cause some flooding. most of that rain will clear during sunday morning, to leave brighter skies behind, but some showers too. and with some colder air digging in, some of those showers will turn wintry, top temperatures between two and 7 degrees. that's all from me. happy christmas.

this is bbc news. i'm freya cole. our top stories: a deal is done — the european union and united kingdom finally reach a post—brexit trade deal — after heated negotiations. both sides hail the agreement a "big success". we have completed the biggest trade deal yet, worth £660 billion a year. a comprehensive ca nada—style free trade deal. it is fair, it is a balanced deal, and it is the right and responsible thing to do for both sides. stalled over christmas — a covid stimulus package, designed to revive