Many moons ago the G8 (once the G7) was just an informal meeting, known as a 'fireside chat'. But by the time I went to Blair's first summit, in Denver in 1997, the event had become a huge junket. The bland statement issued at the end of the bash had been prepared in advance by backroom boffins and we just partied for three days. I've never seen Gordon Brown so grumpy as he attended endless irrelevant functions, days before his first Budget.
More recently Downing Street has been keen to ensure the Chancellor and Foreign Secretary are excluded from such summits in order to give the Prime Minister all the credit for any deals. But Blair had the opportunity to make Gleneagles a joint affair with his chancellor. Indeed, one of his closest advisers tells me that 'Tony could invite who he wanted'.
Leaving out Brown will come back to haunt him.
After all, finance ministers now have their very own little G8 meeting.
And last month it was the Chancellor, not the PM, who announced the historic breakthrough on cancelling developing world debt. With Blair in Singapore for the Olympics decision, Brown was able to bask in the glory of this victory at the 225,000-strong Make Poverty History rally in Edinburgh. He was even interviewed in his garden in Scotland on Monday's GMTV.
Blair's camp realised it needed to fight back. His media advisers got him a gig with Sir Bob Geldof on MTV, but apart from that he has generally been unable to muscle in on the pre-G8 hype generated by the Irish knight, making Blair's job of presenting us with a positive outcome even more difficult.
The fact is that all the aid and debt deals have already been done - and it will look even worse if the media discover there has been any double counting. The only possibility is a good deal on climate change, and given that George W Bush refuses to even accept that global warming is happening, the PM certainly has his work cut out on that one.
With Brown excluded, the Chancellor's confidantes have let it be known that they are quite happy to let the Prime Minister hang out to dry. With the election now won, Blair clearly believes that the Chancellor has become dispensable.
But he could not be more wrong.