It has been revealed that builders did not have planning permission to excavate the three-storey house which collapsed so dramatically in Tooting last week.

Witnesses described an incredible scene as the pavement was sucked into the recently excavated basement at 32 Trinity Road last Tuesday about 4.30pm.

As the pavement gave way, and scaffolding became unsafe, unaware pedestrians and curious onlookers stopped at the scene - just minutes before the house caved in, smashing concrete and scaffolding across the length of the road.

Fortunately no one was hurt as building inspectors - spotting the imminent danger - called police and the fire brigade who sealed off the area.

But travel chaos followed for two days as the area was cordoned off while houses and gas supplies were made safe.

It is believed a small mechanical digger was being used to renovate the house.

Chris Worrall, lived with his fiancee next door at number 30, and returned home just in time to see his roof and bedroom collapse.

Mr Worrall said: "I was visiting a friend, and from their house I saw two cracks appear and then the whole thing fall apart.

"We were supposed to have the day off, so we should have been in. I don't know what would have happened.

"All my stuff is ruined. I'm annoyed, but what can I do?"

The couple are currently living with friends.

Gillian Carver-Chaplin, of Wandsworth Oasis Trading, said: "The glass had already blown out all over the road, but people were still standing outside looking at it, and others were walking under the scaffolding.

"I knew it was going to go, so I called the police. I thought someone's going to get hurt here."

Another witness said: "The pavement was literally falling away, it was amazing no one was hurt."

A spokesman for Wandsworth Council said: "There was no building approval, planning permission or planning notice."

The Health and Safety Executive (HSE) is investigating the incident, the latest in a spate of construction accidents in Wandsworth this year.

Julia Brandreth, union organiser for Battersea and Wandsworth TUC which represents thousands of workers in Wandsworth, said: "It is unacceptable in a civilised society in the 21st century that in Britain 250 people a year go to work and don't come back because they're killed in work-related incidents.

"Thankfully no one was hurt but the HSE need to look at the rising number of these incidents in London and it is worrying that there are only 14 or 15 HSE inspectors in whole of London during a housing boom and lead up to the Olympics."

Construction accidents in Wandsworth in 2008:

April 29 - House collapse in Trinity Road March 20 - Builder dies when five tonnes of marble fall on him in Wandsworth.

March 11 - a 28-year-old builder rescued after the roof collapsed at Tooting Mosque. He suffers minor injuries.

March 3 - scaffolding collapses in Battersea crushing lamp posts and severely damaging parked cars.

January 14 - tree surgeon seriously injured after incident with chainsaw in Beaumont Road.

January 10 - four builders injured at house collapse in Clapham Common - none life threatening.

In September 2006 two men were killed as crane collapses at a Barratt Homes construction site at Thessaly Road, Batteresa.