Ross Kemp's ITV Prison Documentary 'Welcome To HMP Belmarsh' Airs On Thursday

The two-part series sees Ross venture inside the walls of South East London prison HMP Belmarsh, to see what life is like in a maximum security lock-up.

Belmarsh is famed for housing the country's most notorious convicts. Previous occupants include KGB agents, train robber Ronnie Biggs and Charles Bronson. One anonymous prisoner refers to the jail as "Hellmarsh".

Adrian Knight, head of prisoner safety, said: "We will take anyone. We've had war criminals in here for genocide. There's not one prisoner in the country that we won't take. We've got 17 convicted terrorists, 187 murderers, prisoners that have killed three or four people."

Ross spent a period of six months inside the jail with a camera team, gaining full access to the harsh realities of life in prison, where mass murderers, extremists and common criminals live side-by-side.

During that time, the ex-EastEnder went inside the High Security Unit, the only 'prison within a prison' in England and Wales.

Ross also investigates the impact that drugs have on prisons and how Belmarsh approached the rehabilitation of its inmates.

In Thursday's episode, head of prisoner safety Adrian Knight shows Ross the only Contingency Suite in the country, a unit for notorious high-profile prisoners.

Designed for prisoners at risk of suicide or attack by other inmates, over the years it has housed criminals like Soham killer Ian Huntley, black cab rapist John Worboys and hate preacher Anjem Choudary.

Belmarsh also operates as a local prison, taking in criminals from the area. Ross discovers that a rise in gang crime outside the walls is mirrored by increased violence within the prison.

Elsewhere in the programme, Ross interviews prisoner, Muhammad Asif Hafeez, known as the Sultan, alleged to head up a drug-smuggling empire. He is facing extradition to the US and up to 30 years in prison.

Given that no film crew has ever been granted access to the prison before, the documentary promises to be an eye-opening watch.

Welcome to HMP Belmarsh airs Thursday, 9pm on ITV.