A press guy in the States says to me:

If Blair does not return to, and stay in London, he will look back in a few
days and say “what the hell was I thinking?” As will the press, his
constituents and his critics. Of that, I have no doubt. He needs to be
there; comforting Brits, coordinating the response.
He should ask President Bush to do the tough talk in Scotland, while he goes
back where he must be. Now.
My guidance to him would be simple, just use the one-year-later rule: A year
from now, will people remember anything about what happened at the G-8, or
will they remember what happened in London on 7-7? Easy choice.