IT is more than a decade since both Ronnie and Reggie Kray were laid to rest at their family plot in Chingford Mount Cemetery.

But it is a testament to an enduring fascination with the pin-up boys of London’s criminal underworld of the 1960s that a new book about their lives still has mass appeal.

Much has been documented about their reign of terror in the East End and beyond, including a successful film starring Gary and Martin Kemp, but little is known of the decades they spent behind bars for the murder of fellow gangsters James “the hat” McVitie and George Cornell.

Former Daily Express journalist Robin McGibbon, who had written a book about the elder Kray brother Charlie, was introduced to the twins by a mutual friend in 1985 and maintained regular contact with them both until their deaths.

The arrangement was mutually beneficial. McGibbon was happy to provide a steady stream of stories to a public still hungry for news about the pair.

The Krays, for their part, seemed content to oblige, eager to keep themselves in the headlines.

McGibbon’s new book, The Krays: Their Life Behind Bars, contains more than 100 letters he exchanged with the twins and provides a unique insight into how the brothers dealt with life behind bars.

Despite his paranoid schizophrenia and tendency to extreme violence, McGibbon admits he preferred the company of bisexual Ronnie, who was kept in Broadmoor due to his mental instability.

The author accepts this is likely to have been due to the heavy medication which kept him sedated, but he found Ronnie more charming and better company.

He said: “Ronnie was a gentleman and was always well dressed in £500 suits and crisp ironed shirts.

“He was the kind of person, if I took you to Broadmoor to meet him without you knowing who he was, you would come out saying he was a charming bloke.”

In contrast, McGibbon said Reggie was “arrogant and manipulative” and the pair would often argue.

“Reggie still liked having the reputation of being a godfather and the fact that it could get him anything,” he said.

Reggie is said to have remained much the same as he got older, but Ronnie changed after his wife, Kate, wrote a book which detailed an affair.

“After he found out, he changed and became a shambling wreck,” McGibbon said.

“He was embarrassed by the details being made public. I remember going to see him afterwards, and he was just wearing a rugby shirt and faded jeans, which was not like him at all.”

The Krays: Their Life Behind Bars is out now.