No way he would have won that. In the end, the race turned out to be a real war of attrition, with even the marathon specialists struggling and fading. Mo Farah might have had a chance in a sprint finish in a slow race, but London 2013 was the opposite of that.
The real question to me is, given the hot weather (I ran in London, it was hot), why didn't they ask for a more realistic pace? This was clearly not the weather for a world record attempt.
If they want regular shots at a world record in London, they will have to make it an 8 o'clock start. Of course, that would mean much smaller crowds (London's real selling point), so I think they should just forget about records, unless it's unusually cold and a south easterly wind (London is one of the courses where wind can be beneficial).