Horrified onlookers saw a man fall from Putney Bridge into the River Thames during Boat Race dress rehearsals last Friday.
Witnesses said the man, in his 60s and reported missing to police earlier in the day, had asked a pedestrian for a cigarette lighter, lit his cigarette and then hurled himself into the river near Lower Richmond Road.
Two policeman on patrol called a lifeboat and the man, believed to be from Surrey, was rescued and taken to hospital by ambulance. He was later released.
The incident disrupted emergency drills being carried out by Boat Race officials ahead of the following day's contest.
A witness told the Chronicle: "It was really weird. He asked this woman for a lighter, had two drags on his cigarette and just leapt in."
A police spokeswoman said: "A man was seen to fall from Putney Bridge on March 24 at about 16:35. Two police officers on patrol called London Ambulance Service and the lifeboat.
"The man, in his 60s, was recovered. No further action was taken by police. He had been reported missing a short time before."
