The mystery Hatton Garden master-burglar known only as 'Basil' is a former policeman, one of the gang claimed today.

Police are still hunting for the ginger-haired 'brains' behind the £14million gem and gold heist who went on the run while the rest of the seven-strong gang were jailed for 444 years.

Danny Jones, 60, who squeezed into the Hatton Garden vault through a drilled hole with 'Basil', believes the mystery man was once a policeman who remains friends with serving officers.

Wanted man: Scotland Yard have offered £20,000 to track down 'Basil', the brains behind the £14million Hatton Garden raid who is said to have been a former policeman turned security expert

Evidence: In a letter written from jail Danny Jones says that Basil is a police officer

Jones told Sky News in a letter from Belmarsh Prison: 'I can say that someone told me he was an ex-policeman who got into security by the guy who introduced him to me.

Expert: 'Basil' is suspected of being the man responsible for the gang's phenomenal insider knowledge

'He said Basil heard about me from a close friend on the police force, as I was arrested for a similar raid in Bond Street in 2010.

'Basil was the brains as I was recruited by him, he let me in on the night of the burglary. He hid keys and codes throughout the building.

'I saw Basil about four times throughout, he came and went. I don't know nothing about him, where he lives. I wasn't interested.

'I wouldn't give him up as I would grass a grass. It's not a done thing where I come from as [I] fear for family members.'

Jones buried his share of the jewels under two graveyard memorial stones, including one belonging to his children’s grandfather.

In bugged conversations between gang members, Jones also bragged that they had carried out the world’s biggest ‘tom’ raid – Cockney rhyming slang for ‘tomfoolery’, or jewellery.

Meanwhile the master criminal 'Basil' is suspected of being the man responsible for the gang's phenomenal insider knowledge.

He was able to identify the thinnest part of the wall to drill, the layout of the alarm and CCTV and that the most valuable boxes in the vault were on the right hand side.

Yet he is not believed to have any criminal history, with one accomplice noting he learned in 'two months' what took master criminal Brian Reader '40 years'.

Basil was a key player in the raid, who possibly flew into London from overseas to lead the execution of the daring heist.

He used a key to get into the building, before letting the others in and being the first to get his hands on the loot after crawling through the hole.

Despite being repeatedly caught on CCTV, his disguise of a blue cap, surgical mask and ear defenders - and possibly a ginger wig - has left detectives stumped.

They admit they do not even know if Basil is his real name, or simply a nickname inspired by the naughty children's TV glove puppet Basil Brush.

Jobs: John Collins (left) was the driver and lookout for the gang. Daniel Jones (right) got inside the vault

'Career criminals' Terry Perkins (left) and Brian Reader (right) were the ringleaders of the heist. They had already admitted taking part in the raid before last month's convictions

Hugh Doyle, William Lincoln and Carl Wood (left to right) were found guilty of involvement in the raid

The eighth gang member - known as 'Basil' - remains unidentified and at liberty, and Scotland Yard has offered a £20,000 reward for information leading to his arrest

At one stage Basil can be seen towering over 5ft 9ins Danny Jones, the athletic burglary mastermind who joined him on the other side of the hole.

The investigation to unmask him remains 'live' but officers insisted they have little to work on and hope a £20,000 reward could spark fresh leads.

The fugitive could hold the key to the missing millions but it is not clear how much he got away with.

But it is at the very least a six-figure sum, including £82,000 cash, foreign currency and a bag of gold, possibly worth £300,000.

His accomplices joke it could last him a long time as he 'lives cheaply'. They say he will have to 'come all the way over again' to pick up his 'full share', suggesting he may be overseas.

Det Supt Craig Turner said last month: 'This is an ongoing investigation. We are still trying to identify the individual known as Basil.

'There is a £20,000 reward for information that leads to his arrest and conviction, as well as the recovery of the outstanding property.