A benefits cheat set fire to herself in an underground car park after learning her £70,000 con had been rumbled, an inquest heard.

Caroline Grainger, 50, had been impersonating her dead mother for years as she helped herself to her state pensions and disability allowances.

She also claimed carer’s allowance for herself and used the cash to pay rent on a plush mansion block flat, Westminster Coroner’s Court was told.

But Ms Grainger was caught out in October last year when her letting agents became suspicious and launched an investigation.

She set multiple fires at the flat in Fulham, sw London, before driving her blue Ford Escort to a car park in central London.

There, she doused the inside of the vehicle in petrol before sparking another blaze that engulfed her in a massive fireball.

Shocked onlookers watched as she begged them for help as she rolled in a puddle on the floor in a desperate bid to put out the flames.

By the time paramedics arrived at the scene in the basement of Dorset House, Marylebone, Ms Grainger had suffered 85% burns.

She died in hospital nearly three weeks later after major organ failure.

A postmortem found the only area of her body free from burns were the soles of her feet and concluded she had died from ‘widespread full thickness burns’.

Her mother’s ashes, along with caskets containing the remains of seven pet cats, a shotgun and three cartridges and £8,400 in cash inside a plastic bag, were found inside the burnt out car by fire crews.

But a coroner said it was unclear whether Ms Grainger, who had no history of mental illness or social services involvement, had intended to kill herself.

Det Con Anna Petherbridge, of the Met’s Homicide and Serious Crime Command, said investigations had unearthed Ms Grainger’s benefit scam.

When her mother, Fleur Draper, died in June 2009, she did not tell authorities and continued claiming her allowances as if nothing had happened.

Correspondence from her letting agent was recovered from her blackened flat following the blaze last October 10.

‘It shows rent cheques paid from the account of Fleur Draper for three-and-a-half years after the death of Fleur Draper,’ said Det Con Petherbridge.

‘Of more significance, there is a letter dated October 8 from an Yvette Webb, lettings manager, to Mrs Fleur Draper. A copy was found in the flat.

‘More than likely it was delivered on either the day or the day before her death.

‘It says, “I am advised that Mrs Fleur Draper is no longer the tenant, having passed away in 2009”.

‘It goes on to ask for an explanation as to how Mrs Draper could have been communicating with them if she had indeed died.

‘Other letters within the correspondence show Mrs Fleur Draper corresponding with the letting agent.

‘These are dated after the death of Fleur Draper in June 2009 but purported to be from her – in the letters she makes reference to her daughter.

‘The caretaker was unaware Fleur Draper had died in 2009 and stated Caroline Grainger had continued to refer to her mother as recently as a few weeks prior to her own death.

‘She mentioned she was clearing out some clutter from the balcony so her mother could sit outside in the spring.

‘It appears the deceased was maintaining her mother was still alive.

‘The reasons are not entirely clear but it may be so she could continue the tenancy, which was in her mother’s name.

‘This letter showed they had discovered it.’

Over the three years following her mother’s death, Ms Grainger was paid a total of £41,134 in state pension, disability living allowance and pension credit.

She also received an annual £9,000 carer’s allowance.

Fire investigator Garry Warren said it was fortunate the Dorset house fire had not spread to the ten-storey art deco block above or to an adjacent petrol station.

Around 150 residents of the Grade II-listed block on Marylebone Road, where flats sell for up to £1 million, were evacuated after smoke started to fill the lobby but they were later allowed to return.

Mr Warren told the court the car park’s sprinkler system had activated and confined damage to the inside of Ms Grainger’s car.

The fire at her first-floor flat was also prevented from spreading after a passerby out walking in a nearby park reported seeing smoke billowing from the windows.

Both blazes were started with petrol, and Ms Grainger had also tried to start secondary blazes in the flat by setting fire to a duvet and a suitcase full of personal letters.

After she was discovered following the second blaze, Ms Grainger was taken by air ambulance to the specialist St Andrew’s Centre for Plastic Surgery and Burns in Chelmsford, Essex.

She died there on October 27 after suffering major organ failure, despite intensive treatment.

In a statement read to the inquest, Professor Peter Dziewulski said: ‘I’m sorry. We could not deal with this poor lady.’

Coroner Fiona Wilcox recorded an open verdict, saying she could not be sure whether the death was a suicide or an accident.

She said: ‘The evidence – the burning of the home, the burning of the car, the whole extraordinary circumstances – point to someone who cannot have been thinking clearly.

‘But whatever her intention at the time she lit the fire, at the time of her death she was asking for assistance.

‘Because of this I do have a reasonable doubt as to her intention to take her own life and therefore I’m unable to record a verdict of suicide.

‘However, I’m also not able to record a verdict of accident, since again I don’t know whether the fire that started on her clothes and led to her death was an accidental occurrence arising out of her soaking the area in accelerant and then igniting a match, or whether that was deliberate.

‘I therefore have no choice but to record an open verdict in this case.’

The coroner added: ‘She had recently been discovered to have been fraudulently claiming benefits and paying rent in the name of her mother, who had died in 2009.

‘But there is no evidence she intended to take her own life.’

The inquest was told both Ms Grainger, born in Hampstead, nw London, and her mother were only children and have no next of kin.

Verdict: Open.