Hasib Hussein; I am still wondering why he couldn't get on a train.
Thinking about the 3 tube bombers - the Aldgate/Liverpool St one and the Edgware Rd one are both 4 to 5 stops away from King's X. So, assuming they all split up and entered the Underground at the same time (which is an assumption, admitedly), was the King's X/Russell Square one delayed also? Perhaps that bomber intended to detonate at Leicester Square/Piccadilly Circus (again, 4-5 stops away from King's Cross), but was delayed, since the bomb went off only half a stop away from King's X (King's X/Russell Square).
Could it be that because of the earlier unconnected delays on the Piccadilly Line (line closed between Arnos Grove and King's X due to suspect fire at Cally Rd, reopened 8.28AM according to Transport for London), it was extra crowded and he had difficulty getting aboard a train?
But how this relates to the bus bomber I am not sure - it has been said that he was attempting to get on the Northern Line, but how is this known? Maybe the police have evidence of this - CCTV, eyewitnesses? Or maybe its just more media supposition. Suppose he was intending to get on the Piccadilly Line also? Couldn't get on several trains due to overcrowding, then at 9AM the station was evacuated so he came up to the surface and the McDonalds?