this is safa's brain, that's marwa's brain. what we need to achieve is to effectively untwist the brains, and that is difficult, pretty difficult to do just in your head. but it is perilous. the pads are on and they are ready to shock if we need to. 0k. the bbc was given unique access to chart the complex medical and ethical choices made... this is the day, the moment of truth, and everything hasjust got to be perfect. ..in the hope of giving the girls independent lives. safa and marwa are 21 months old, and were born in pakistan. they have come to london's great 0rmond street hospital with their mother, zainab, grandfather and uncle, and are under the care of neurosurgeon 0wasejeelani. it is clearly very difficult to go through life when you are joined together like that, so it does make a very persuasive case in favour of doing... attempting the separation. the family are very clear on that. clearly, i think life being separate is better than being joined together. if we felt there was not a very, very high chance that we cou