joining me now is a former commander of special operations at scotland yard. this is a case of needs must. first of all, take us through the advice in the past where it wasn't thought to be a good idea to shoot at moving vehicles. was this because of the danger of bullets ricocheting off the vehicle? partly that but partly the fact that if you shoot at a musing, removing vehicle and incapacitate the driver then that vehicle could career into innocent people, kill pedestrians, cause a significant road traffic accident. the vehicle is perhaps escaping the scene of crime being used for crime, and not being used for a weapon. what we are seeing is a different situation where the vehicle is a weapon. as i said to begin this interview, it is a case of needs must. if police believe that someone is going to use the vehicle as a