There still seems to be a lot of doubt as to exactly how the bombs were triggered, or in other words whether or not the killers were true suicide bombers rather than own-goals or unwitting assassins. Amongst other things, property belonging to one of them was found at both the Edgware Road and Aldgate explosion sites. Now, no-one has ever managed to blow themselves up twice, and I'd hazard that no-one ever will, so either one of the other killers was carrying some of the other's goods (why? how?) or one of the bombs was placed on a train and detonated by a timer, while the bomber set off to bomb a second train. That, of course, would cast doubt on whether or not the other bombers were intentional suicide bombers.
There's a lot of tinfoil hattery bubbling about around this. I will only say that what is most important is that bombs were exploded, and that all the bombers seem to have died in the attack. The Postman argues that they might have been recruited to move drugs and that they were under the impression this was another load. Well. I suppose it's a possible explanation, but without more support, I feel most of the non-suicide/unwitting assassin theories are wishful thinking.
The latest source of doubt is that, apparently, they bought return tickets at Luton station and paid the parking fee. Well, buying a return ticket is not the obvious act of a suicide bomber, but there is a historic precedent of a sort. On the 21st October 1916, the Austrian prime minister Karl Graf von Stürgkh was assassinated in the Hotel Meissl und Schadin's restaurant on the Hoher Markt in Vienna as he enjoyed a post-lunch cigar. Stürgkh, an unmourned militarist thug on the far right of political Catholicism who had campaigned vigorously for war, had unknown to himself convinced Friedrich Adler, editor of the Arbeiter-Zeitung (Workers' News), that he was a tyrant bent on expanding the war after he refused to allow parliament to be recalled. Adler sat down at a table, drank two glasses of beer, paid his bill, then drew a revolver and shot the prime minister three times, before sitting down to await the arrival of the police.
Adler was put on trial, but the trial was interrupted by the army authorities on the grounds that his speeches from the dock were a subversive influence. Instead a secret military tribunal sentenced him to death, but the death of Emperor Franz Josef II and his replacement by Karl I, who tried to get out of the war, led to his sentence being commuted to life imprisonment. The revolution of 1918 released him. He outlived everyone else involved, including the restaurant once famed for offering 14 different kinds of Tafelspitz, which was destroyed by the RAF one night in 1943.