My view on this has always been that Blair had become a liability for Labour long before 2005 and that had Brown been leader at the last GE the party would actually have won a majority in excess of 100, but Mike disagrees and thinks that if Blair were still leader the Tories' lead now would still be only in single figures.
Most of the posters on PB.com sided with Mike on this but there was some support for my point of view from the distinguished pollster Robert Waller who made the following very interesting comment:
"By 2005 Blair was a very significant disadvantage to Labour, with Professor Harold Clarke and other academics using the British Election Study claiming that there would have been another 100 plus landslide majority if he had not been PM at the last general election.
"Thereafter, he did have to go, forced out earlier than he intended by pressure within various sections of the party culminating in the ‘plots’ around the time of the Lebanese invasion/crisis.
"With his party as well as the public thoroughly fed up with him, there was no possibility of remaining; the massive sigh of relief was the cause of the ‘Brown bounce’ (that really wasn’t Brown’s attractions!) in the third quarter of 2007. If for some reason Blair had managed to avoid all the pressure to go in mid 2007, the head of steam of ‘time for a change’ would just have got stronger and stronger.
"In addition he would have faced almost all the significant problems Brown does, unless he would be able to work a miracle with the oil and other commodity prices and economic peessimism which are the reasons for Labour’s current dire position in the polls. They would surely have been even worse off under Blair."
Ultimately, of course, as one other poster pointed out, all such counterfactuals are meaningless. But they are good fun, nevertheless.