Revealed: Plans for mega-basement extension being built beneath £8.5million Chelsea mansion before it suddenly COLLAPSED ‘in thunderous crash’

A Chelsea mansion worth £8.5million has collapsed during mega-basement construction work in the heart of the celebrity-filled suburb. 

Neighbours reported hearing a huge thud as loud as thunder in the middle of the night as the mid-terraced house was completely destroyed. 

Emergency services were still at the scene this morning in Durham Place, London, where fire crews worked through the night to secure the buildings.

The neighbourhood has been home to super-rich businessman and celebrities as Roman Abramovich, Amanda Eliyash and Mick Jagger.

Pictures of the devastation show the huge mid-terraced house reduced to rubble behind a cordon set up by police.

The London Fire Brigade said at least 40 people have been evacuated from surrounding buildings. 

A close neighbour told how he was woken in the early hours of the morning by what he thought was a loud thunderclap.

He said: 'There was just a huge thud. I thought it was thunder but there was only the one loud thud. It wasn't until the morning on my way to work that I saw the building had collapsed. There were lots of police and the road was sealed off.

'Workmen have been there for weeks excavating a basement. I don't think anyone was in the property at the time but it is going to be very expensive to fix.

'The roof has just collapsed inwards and taken down the whole of the inside.' 

Another said they heard a ' huge crash ' and ran out of their flat to see the building next door had collapsed.

She said:  'We were still up and just heard a huge crash . We ran outside and the building next door had disappeared.

'We knew it was empty but called the police. Lots of police and ambulances turned up, but no one was injured.

'A few hours later and there would have been 10-15 builders inside.'

Land registry documents show the freehold of property is owned by Seabrook Properties Limited, which was set up in the British Virgin Islands.

A planning application, approved last year, had been granted for works to the lower ground floor and terrace above.

It also mentioned a rear extension to lower ground floor with terrace on upper level.

The application added: 'All box sash windows to be replaced with painted timber, with double glazed sashes. 'Timber glazed bi-fold doors to upper ground floor level. Reinstatement of pitched roof and 8 no. conservation rooflights. Brickwork replaced.'

The Royal Borough of Kensington and Chelsea had warned at the time 'Advice should urgently be sought if a problem occurs during approved works'. 

The mid-terraced houses were completely razed to the ground in the middle of the night in upmarket Chelsea 

Met Police said they received reports the buildings had collapsed last night and crews have been working to secure the scene

The scene in Durham Place in Chelsea, west London, after two mid-terrace houses collapsed

Reports suggest the £6 million properties were being converted into one home and construction work was ongoing

Plans showed the owners wanted to extend the basement three metres further and add a new upper terrace, shown in black

New steps from the new basement to the garden and then to the upper terrace were also shown in the new design drawings

First and second floor plans said brickwork was to be repointed and replaced where necessary and new window sashes in

The devastation of the multi-million-pound property minutes after it collapsed into the ground early this morning

Emergency crews lit up the property after it fell into itself in the early hours of today with rubble and wreckage strewn aside

One man, who was evacuated last night but had come back today to look at the damage, said: 'I was in the house next door and at about 11:30pm last night we heard it coming down.

'At first we heard what I assume to be the scaffolding and the rest of the building.

'We ran outside and I was left standing outside in my pyjamas with just my phone.

'We had to get out and weren't allowed back in. We don't know when we can come back in. I think it's going to be a while until we can. It was derelict and under renovation.'

Homes in Durham Place, a short distance from the Royal Chelsea Hospital, sell for over £10m. Many of the four-storey homes overlooking a private green are converted into flats.

The fire brigade have confirmed the two mid-terraced houses of four floors were under construction when they collapsed to the ground.

The Brigade's Urban Search and Rescue crews worked to make the scene safe until 2am and there are no reported injuries at this stage. 

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The back of the property showed the terrible damage done to the building caused by the collapse earlier this morning

Two mid-terraced homes in Durham Place, Chelsea, have been completely destroyed after they collapsed late last night

Crews put a 25m cordon in place and worked through the night to secure the construction site after evacuating neighbours

Emergency services have put a cordon in place and the London Fire Brigade said that around 40 people have been evacuated

The fire brigade confirmed construction work was being carried out on the properties, said to be worth up to £10 million

Engineers and construction workers at the scene where the £6 million mansion was under construction before it collapsed

Around 40 people were evacuated from neighbouring properties and a 25m cordon was put in place as a precaution by the Metropolitan Police Service.

Station Commander Jason Jones, who was at the scene, said: 'There was a total collapse of the building from the roof to ground level.

'Firefighters worked to make the scene safe and our drone team carried out a search.

'A police search dog also carried out an external search of the building and at this stage, there are no reports of any injuries. Nobody is thought to have been inside the building at the time of the collapse.

'Local road closures will remain in place this morning.'  

The Metropolitan Police confirmed in a statement: 'Police were called at 23:25hrs on Monday, 2 November, to reports of a building collapsed in Durham Place, SW3.

'The occupants of neighbouring properties have been evacuated as a precaution.

'At this stage, there are no reported injuries and nobody is thought to have been inside the building.

'Emergency services remain at the scene.' 

One fire engine from Chelsea Fire Station and three fire rescue units from Battersea, Sutton and Croydon fire stations were at the scene but have since left.