The results are in: I finished 2,763rd among the 34,000+ finishers, in a time of 3:17:36 . I came 579th among fortysomething men but was beaten by Scooby Doo.
More importantly, NCH, the children's charity, will be able to bank more than £4,000 after giftaid, thanks to the generosity of my sponsors.
It was a fantastic experience. In the first mile, a priest stepped out of his church to spray holy water in the direction of the runners. That sort of spirit continued along the route, with noisy crowds several deep lining the final, painful miles.
I've lived in London almost 20 years and it's not the friendliest city on the planet. But marathon Sunday is the one day in the year when Londoners of all colours and backgrounds talk to - and cheer for - strangers. It kept me going.
The marathon is a unique event. In what other sport can middle-aged plodders take part alongside the world's finest? It really is the taking part that counts, especially for the thousands of us who stand no chance of winning.
I was beaten by Elvis, and several men in tiger print loin cloths. I fear Borat in his mankini may have arrived at the finishing line ahead of me, but it was an incredibly uplifting day.
A word for my sponsors. Politicians and their staff often enjoy a reputation somewhere between that of estate agents and journalists. They are often badgered for cash by good causes. Many are already committed to their own charities, but still gave willingly to mine - in some cases without being asked.
Five of the Liberal Democrat members of the Welsh Assembly coughed up, as did three of the party's four Welsh MPs (there are absolutely no prizes......).
I'm no Lord Levy. Fund-raising, even for a good cause, is not a pleasant experience, although you do learn a lot about human nature when you ask people for money. Getting cash out of some highly-paid executives proved harder than running the race.
I'm still trying to work out whether rich people are rich because they're tight-fisted, or tight-fisted because they're rich and want to hang on to the cash.
But the generosity of sponsors, and the total raised, far exceeded expecations. If you didn't get around to sponsoring me, you'll be delighted to know there's still time - see the link on the right.
Forgive the self-indulgence in a blog that is normally about other people. Normal service will be resumed once Parliament returns on April 21.
I'm off to negotiate the stairs.....I may be some time.