Ben Fairhead sent in a picture of the burst main

London Fire Brigade (LFB) said it received a call about the leak at the junction of Maida Vale and St John's Wood Road at about 0600 BST.

Thames Water said they received calls from 650 homes who had lost their water supply or water pressure.

Engineers managed to stop the leak at about 1135 BST after five hours.

All those who were evacuated from their houses have returned home, and repairs on the pipe are underway, but local traffic diversions and road closures remain in place.

Clifton Road was worst-hit by the cascading water that gushed out of a large 36-inch pipe, a Thames Water spokeswoman said.

Underground car park

The A5 Maida Vale is closed both ways between Elgin Avenue and Blomfield Road and northbound queues have formed from Marylebone Flyover.

The A5 Edgware Road northbound traffic is heavy with slow moving traffic towards Maida Vale, and traffic is also heavy and slow moving in St John's Wood and Lisson Grove.

Traffic is being diverted northbound through Aberdeen Place and southbound into Elgin Avenue.

The Thames Water spokeswoman said: "The situation now is that we've managed to shut the water main off, so there's no more water actually flowing down the street.

At least 300 houses have lost their water supply. Pic from Tom Dowman

"There are a number of properties that are currently without electricity and we are working with an electricity company to try and get that repaired as quickly as possible.

"Obviously there are some elderly and vulnerable people here so we want to make sure that they are looked after."

The spokeswoman said Thames Water hoped to have finished the repairs by 19 October.

One local resident said: "It's happened twice since I've been here. It's been, I wouldn't say on the same spot, but I'm pretty certain that last time it happened just across the street."

'Swiss cheese' pipes

The Thames Water spokeswoman said: "The difficulty we've got in this area of London is we've got very old Victorian water mains, some of them as old as 150 years.

"The are like Swiss cheese, they've got holes in them, they leak and they burst.

"What Thames Water is doing at the moment is a massive programme of investment to replace them all around London."

Westminster Council had taken the evacuees to a nearby pub for shelter before they returned home.

A BBC London travel reporter said the road surface had started to break up because of the water.

Bus routes 6, 16, N16, 46, 52, 98, N98, 187, 332 and 414 have been diverted and are likely to remain so for a week.