The 41-year-old returned to the scene of her greatest triumph – her staggering world record of two hours, 15 minutes and 25 seconds set on the streets of the capital in 2003 – to bid an emotional farewell to competitive marathon running.
The days of running those sorts of times are over, but the cheers from the crowds lining the streets were as loud for her as for any of the champions as she came home in an unofficial time of 2hrs 36mins 55secs.
An emotional Radcliffe shouted “thank you” to the crowds as she rounded the final turn and came down The Mall hand in hand with a club runner – a homage to the first edition of the event when joint winners Dick Beardsley and Inge Simonsen crossed the line holding hands.
She embraced her husband Gary Lough and children, daughter Isla and son Raphael, at the finish.
“Down the last mile I thought, ‘I don’t care about the time’. I just wanted to thank as many people as I could,” Radcliffe said.
“You can’t come to the London Marathon and not give an honest effort. But I went off way too fast. From then on it got more and more emotional.
“There was a big sign at Embankment saying ‘We will miss you’, but it won’t be as much as I will miss you.
“It was so loud, my ears were ringing. It was just amazing the whole way round. All the way along, there were so many people giving me encouragement.
“I came into this race totally unprepared and hoped the magic of the London Marathon would help me and I’m sure it did. You can’t help but come here and run hard. You have to give it your best effort, and that’s what I did.
“When I knew I was going to finish, I just wanted to thank as many people as possible.”
Lough was scarcely able to speak as he choked back tears.
Radcliffe, sporting her trademark sunglasses and beaming from ear to ear, set off not with the elite athletes, but the masses, alongside the enthusiastic club runners and the charity competitors in their animal costumes.
Her competitive juices were clearly still flowing, though.
She said before the race it would not be a day for high fives and there was no stopping for BBC interviewer Denise Lewis on Tower Bridge.
Despite her hampered preparation – she had to battle one final Achilles injury to make the start line and ensure the crowds witnessed the instantly recognisable head-bobbing style one last time – her time was still inside the IAAF qualifying standard for the Rio Olympics next year. Brazil, though, is unequivocally not in her plans.
After all, Radcliffe’s career has brought a hat-trick of marathon titles in London and New York, a World Championship gold over the distance, European and Commonwealth titles on the track, two World Cross Country Championship golds and, the crowning glory, the marathon world record.
Her mark is a staggering time, almost three minutes faster than any other woman has ever run. Indeed, Radcliffe holds the fastest three women’s marathon times in history.
Olympic medals may be absent – injury or illness or both defeated her in 2004, 2008 and again in 2012 – but her status as one of the finest athletes Britain has ever produced is secure.