David Teale has opened up about the experiences of living with the Kray twins and the 'two weeks of mayhem' he endured when they took over his flat.
He says they kept him, his wife and young family hostage after Ronnie shot rival gangster George Cornell.
The horrific ordeal began on Wednesday, March 9, 1966, two days after David's 23rd birthday.
David was with his brothers Alfie and Bobby when Reggie rang and insisted they went down the pub round the corner in Bethnal Green.
David said: "I’d first met the twins when, six years previously, they’d muscled in and taken control of the Tudor Club, the nightspot my parents ran in Islington, keeping most of the weekly takings for themselves.
"Dad was too old to fight them and Mum was heartbroken. But, like Alfie and Bobby, I was flattered by the attention these powerful men in their flash suits gave me."
As a teen, David and his brother Alfie would sell jewellery and perfume out of suitcases on the street before he started completing errands for the notorious Krays.
It included sticking stamps on envelopes for hours, of letters Ronnie wrote to families of those he'd "cut up" to "make amends".
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On the night of being invited to the pub, Reggie told him George Cornell, who once called Ronnie a "fat poof", had been seen in the Blind Beggar pub in Whitechapel.
Ronnie had gone and shot him in the head in front of all the customers, and now he and The Firm - those who worked for the twins - needed somewhere to hide out, David writes in the MailOnline.
David says: "Later I discovered that the only reason they [the police] didn’t come in guns blazing was because they knew that the Krays were capable of using the kids as shields to get out. Instead, they checked up on us periodically."
The couple were allowed to go out to the shops but one of their children would be left at home with the twins as a 'hostage'.
Later, David was put in prison along with his brothers for blackmailing a wealthy man named Bobby, who turned out to be a police informant, which David claims was part of a plan to keep them protected while a case against the Krays was built.
He also speaks of being surrounded by armed police while in the witness box at the Old Bailey.
He said: "I tried to act tough but I’d never been so scared in my life. Across the courtroom, I could see the Kray twins sitting in the dock. Staring me out, hissing, muttering, Ronnie seemed especially angry.
"‘Grass,’ he whispered. ‘F*****g grass.’"
The 1969 trial of the twins saw the pair sentenced to life for the murder of George Cornell and Jack 'The Hat' McVitie, an armed robber.
Ronnie died of a heart attack in Broadmoor Hospital in 1995, and Reggie in his sleep following a cancer diagnosis in 2000. Reggie was freed on compassionate grounds and spent his final weeks with his wife of three years, Roberta.
David Teale details the ordeal of the Kray twins and his time working with them in his new book, Surviving The Krays, due to be published by Ebury on March 18.