It's probably not going to be a John F Kennedy 'remember where you were?' moment but the day Boris Johnson ousted Ken Livingstone and became the first Tory mayor of London is extremely significant.
David Cameron's Conservatives now have something high profile to run. They've got a fair amount of time on their hands so they can concentrate a lot of effort - and people - on the job.
Boris will be the front man and provided he doesn't fall flat on his face, like Labour ministers no doubt hope, the Tories will have something recent to point to so they can say 'look we're no longer the Conservative Party that John Major led and yes we can do government'.
Home Secretary Jacqui Smith told me on Friday lunchtime - when the result was a very long way from being declared - that she thought the Tories were set to take the mayoralty. She observed that finally they would be tested in running something - presumably because she assumes they will mess things up. But what if they don't?
Labour was prepared for a pretty dire outcome from the 1 May 2008 elections - though not as dire as it turned out. If you were listening to the coverage of the elections in past 48 hours, virtually every commentator said that we would now see a raft of policy initiatives from ministers. Smith said in our phone conversation that she herself would be making an announcement next week. They say they are also going to be listening and learning...
The question on my mind today, though, is what will the Blairites be doing this weekend and in the coming days? Charles Clarke has already chucked a couple of bricks over the parapet at the Brownites but will we hear from Milburn, Byers and the like and, if so, will they take advantage of choppy waters and rock the boat?
Last night I was in the BBC London studios to sound off on the Tessa Dunlop radio show - well, it's cheaper than therapy. As the results came it was incredibly disappointing - and not just because Ken Livingstone lost. It's because the Tories now feel dangerous again and I can't forget what it was like the last time.
Communities abandoned, appalling economic mismanagement, kids educated in portacabins, teachers and nurses paid a pittance. And all the while, tax cuts for the wealthy. Other people seem to have shorter memories.
Personally I hope Gordon Brown is ready for a long, hard two-year fight because the electorate clearly needs to see, in the words of Rhodri Morgan, some clear red water between the prime minister and the PR men that front now the Tory Party.
No more of this big tent stuff - remember "best when we're Labour"?...