Watch video footage taken by a London lifeboat crew after a dramatic night-time river rescue.
The victim, a man believed to be a tourist in his twenties, was found clinging to the upstream side of a driftwood collecting barge floating in the middle of the River Thames near HMS Belfast shortly after 8pm on Wednesday.
Lifeboat helmsman Chris Walker said: "The casualty was in a very precarious position indeed. There was a 2-3 knot tide running at the time of the call, had it been a faster spring tide, he could very easily have been sucked under or even into the collecting hopper where among the rubbish and debris it would have been very hard to get him out."
Following reports that a second victim was in the water, the lifeboat quickly handed the man over to a waiting ambulance at St Catherines Dock before being joined by the police boat, London Fire brigade boat and a police helicopter in an extensive search of the area.
No-one else was found.