Paula Radcliffe destroyed her rivals to win her third London Marathon title in two hours, 17 minutes and 42 seconds.
The world record holder struck out on her own after six miles and but for an unscheduled toilet stop in the 22nd mile maintained a relentless pace.
Radcliffe posted the third fastest women's run with Romania's Constantina Dita over five minutes back in second.
Kenyans Susan Chepkemei, who finished third, and Margaret Okayo paid for trying to stay with Radcliffe early on.
The only moment of drama for the Briton came late on when she stopped by the road-side and squatted down for about 10 seconds before resuming the race.
"I think I need to apologise to the nation for having to stop like that but I was losing 10 seconds every time my stomach cramped up," she said.
"I must have eaten a bit too much, I waited a bit too long. I didn't really want to have to resort to that in front of hundreds of thousands of people.
"I didn't know how far ahead I was because the crowds were so loud and nobody was shouting out any gaps to me.
"I kept thinking 'do I have time to stop?' but then I had to stop.
"I was annoyed because I was feeling good. I went through the first half feeling great and thought I could run hard in the second half.
"It was a similar problem to Athens but there was no danger of me being glycogen-defeated again. I knew if I stopped I would be able to get rid of the cramp and concentrate properly again."
Radcliffe soon picked up the pace again and her winning time was the fastest ever in a women's-only race, beating the previous best of 2:18:56 she set on her on her debut in 2002.
Two years ago she set the world record of 2:15:25 when she ran with the men, but insisted victory - her fifth international marathon win - was the main goal this time.
"It was about winning again," she added. "A lot of people thought that after what happened in Athens I was never going to be the same again.
"My mind pushed my body as far as it would go in Athens but today my body felt good.
"Obviously I would have loved to have run a personal best but I have still run a fast time in the conditions."
Chepkemei, who ran Radcliffe so close in New York last November, finished over six minutes behind in 2:24:00.
Last year's winner Okayo was fourth in 2:25:22 while Ireland's Sonia O'Sullivan posted a personal best of 2:29:01 in finishing eighth.
London Marathon - Women's result:
1. Paula Radcliffe, Britain, 2 hours, 17 minutes 42 seconds.
2. Constantina Tomescu-Dita, Romania, 2:22:50.
3. Susan Chepkemei, Kenya, 2:24:00.
4. Margaret Okaya, Kenya, 2:25:22.
5. Lyudmila Petrova, Russia, 2:26:29.
6. Benita Johnson, Australia, 2:26:32.
7. Joyce Chepchumba, Kenya, 2:27:01.
8. Sonia O'Sullivan, Ireland, 2:29:01.
9. Mulu Seboka, Ethiopia, 2:30:54.
10. Mara Yamauchi, Britain, 2:31:52.