Sir Keir Starmer’s firebombed £2million house was reportedly being rented to his sister-in-law for a peppercorn amount as MailOnline can today reveal a 4×4 torched outside on VE Day was once owned by the Prime Minister.

A 21-year-old suspect has been arrested by Scotland Yard’s counter-terrorism unit on suspicion of arson with intent to endanger life in relation to three blazes linked to the PM. He remains in custody.

Sir Keir’s four-bedroom family townhouse in Camden had its front door doused in an accelerant and was sent alight in the early hours of Monday morning.

It is being reported that since entering No 10 Downing Street last summer, Sir Keir’s sister-in-law has been living there. It is not known if she was at home at the time. The Prime Minister’s official spokesman declined to comment today.

The rental agreement is declared through the ministerial register of interests – but because the rent is below £10,000-a-year threshold, it is not on the MPs’ register. 

An alleged arsonist was held in South London this morning after the doors of two homes linked to the Prime Minister in north London both suffered fire damage within 24 hours of each other, one in the early hours of yesterday and another in the early hours of Sunday.

There was also a vehicle fire on the same street as the latest door attack, last Thursday, that is now being connected to Starmer in a potential arson spree targeting the PM.

The Toyota Rav4 torched on Thursday once belonged to the Labour leader before he sold it to a neighbour after winning the general election, sources have confirmed to MailOnline.

It is understood that the perpetrator chose to target the car due to its association with Sir Keir amid claims the suspect bore a ‘personal grudge’ against the PM.

Today MailOnline revealed the shocking moment the 4×4 burst into flames in an explosion now being investigated by Britain’s counter-terrorism police.

Exclusive footage emerged hours after a suspect was arrested. 

The same hybrid SUV was pictured in October 2020 when Sir Keir was involved in a minor accident with a Deliveroo cyclist in north London.

The collision, which happened near his home in Kentish Town, left the cyclist with an injured arm and the vehicle was photographed with a number of dents and scratches.

The current owner of the vehicle, a neighbour of the Prime Minister, is understood to have thought that the fire started because of a faulty battery. The hybrid car was completely destroyed.

But after two suspected firebomb attacks on properties in North London linked to the Prime Minister on Sunday and Monday, Scotland Yard’s SO15 counter terrorism command stepped in. 

One neighbour, who asked not to be named but witnessed the car fire, told MailOnline: ‘Initially the police did not think it was a criminal case. It was a hybrid car so they just assumed it was some sort of electrical fault that sparked it.

‘It was in the middle of the night, it woke us up, it was scary.’

Great grandmother Linda, 80, who lives on the street told MailOnline: ‘At 3am on Thursday morning I woke up to the sound of people – delivery men apparently – screaming “fire, fire” and the sky outside was lit up.

‘And I thought OMG what’s going on. And I looked out and saw the fire.

‘I saw the car on the road was on fire. I’ve never seen anything like it. It was so bright. Blazing.

‘I saw two fire trucks arrive and it took them a long time to control the blaze.

‘The tree and the front wheel of a neighbours’ bike was scorched as well.

‘The car belongs to our next door neighbours but they’re not the people who [live in] Starmer’s house’.

A witness to the car fire told Metro today: ‘There were bangs and the a huge fire. My bike was parked next to the car it’s tyre was split by the heat. It was very shocking.’

Another said: ‘It was crazy there were proper big flames you could feel the heat coming off.’  

The 21-year-old was held after the doors of two homes linked to the Prime Minister in north London both suffered fire damage within 24 hours of each other, one in the early hours of yesterday and another in the early hours of Sunday.

There was also a vehicle fire on the same street as the latest door attack, last Thursday, that is being connected to Starmer in a potential arson spree targeting the PM.

Scotland Yard is probing whether the blazes are linked and said today that the arrest relates to the three incidents.

Sadiq Khan told LBC that the Prime Minister’s family were ‘scared’ following the attacks.

The London Mayor said: ‘The point I’d make to this issue is, look, don’t underestimate the ripples of fear that, Keir is quite stoic, but you know, Vic and the kids felt when they will have read this stuff in the paper, right? But for the grace of God. And yes, they are safe thankfully, in Downing Street, they’ve got protection team with them, but they will have felt scared, frightened.

‘The neighbours on this street, you know are horrified.

‘I want to thank and commend the police for their swift action, but also the London fire brigade as well. But it can’t be right that any politician and their family faces these sorts of threats. And the context is that in the last 10 years, we’ve had two politicians losing their lives in this country, David Amess and Jo Cox. Of course, we’ve had other politicians like Stephen Timms stabbed and other politicians requiring 24-hour security from police experts.’

Counter terror cops launched an investigation into the latest blaze at the premier’s £2million townhouse yesterday morning where neighbours had heard a ‘loud bang’.

Officers were searching gardens nearby for a projectile with one neighbour telling MailOnline it may have been a firebomb attack. 

Starmer, his wife Victoria and their children moved into an apartment in 10 Downing Street after the election last July.

Investigators believe that the fire at the previous home may have been started deliberately in the middle of the night. 

It is currently being ‘treated as suspicious’ as investigations continue into the cause of the blaze. 

The PM has thanked the emergency services with his spokesperson saying they were unable to comment further.  

A Met Police spokesperson said: ‘The 21-year-old was arrested in the early hours of Tuesday, 13 May on suspicion of arson with intent to endanger life.

‘He remains in custody.

‘The arrest relates to three incidents.

‘On Monday, May 12, at 1.35am, police were alerted by the London Fire Brigade to reports of a fire at a residential address in NW5.

‘Officers attended the scene. Damage was caused to the property’s entrance, nobody was hurt.

‘As a precaution and due to the property having previous connections with a high-profile public figure, officers from the Met’s Counter Terrorism Command are leading the investigation into this fire. Enquiries are ongoing to establish what caused it.

‘The investigation team are also considering two other incidents – a vehicle fire in NW5 on Thursday, May 8 and a fire at the entrance of a property in N7 on Sunday, May 11 – and are investigating whether they may be linked to the fire in NW5 on May 12. 

‘All three fires are being treated as suspicious at this time, and enquiries remain ongoing’.

Sources told MailOnline that Scotland Yard’s SO15 counter terrorism command’s investigation is understood to be routine given the high-profile nature of the owner. 

The fire is said to have only damaged the porch of the property with the door and brickwork charred and black. The blaze did not spread further indoors.

It is not known if the property was occupied at the time, but no one was hurt.

Forensics officers were combing for evidence outside the property all day after the blaze broke out at 1.11am. 

Neighbour Charles Grant, 66, told MailOnline officers had been searching his garden for a projectile that someone may have thrown into the rear of his property, but they did not find anything. 

‘From what other people on the road have told me is that someone tried to throw a firebomb into Keir Starmer’s house – but nobody was hurt, and I don’t think the damage was too extensive,’ he said.

‘The front door of Starmer’s house is shut and still standing. The door and the brickwork is charred and black and it smells of burnt stuff.

‘The police said the damage is not extensive – just needs a bit of paintwork.’

London Fire Brigade (LFB) confirmed there has been ‘damage’ caused to the front of the home with the flames being brought under control by 1.33am. 

A next door neighbour described the fire as ‘scary’ and told how he had been woken up in the early hours by the attack.  

‘It was a loud bang, what sounded like glass shattering. It was scary,’ the male neighbour, who did not wish to be named, told The Sun.

According to the PM’s entry in the register of ministerial financial interests, Sir Keir rents out the family home.

Pictures show the front porch area charred where just five years earlier Starmer and his wife Victoria stood to applaud the NHS during the height of the coronavirus pandemic.

The Metropolitan Police is investigating the blaze, with a spokesman for the force saying officers were alerted at 1.35am.

Sales director Cory Adshead 48, who has lived on the road adjacent to Starmer for three years, told MailOnline: ‘At 1am I heard police sirens.

‘It was a loud bang, what sounded like glass shattering. It was scary,’ the male neighbour, who did not wish to be named, told The Sun.