The Nazi-obsessed killer of MP Jo Cox is now on suicide watch after being jailed for the killing of the mother-of-two.

Thomas Mair pleaded not guilty to all charges in relation to killing Mrs Cox just a week before the Brexit vote. But he was convicted of shooting her at point blank range with a sawn-off shotgun as well as stabbing her multiple times with a dagger.

He has now been incarcerated in London’s notorious Belmarsh prison, where he is told he will die, for the horrific killing of the Labour MP in June. Also in Belmarsh are Michael Adebolajo and Michael Adebowale, who murdered Fusilier Rigby, 25, in Woolwich, south London, three years ago.

Mair is being housed in a special secure unit, where some of Britain’s most dangerous men are jailed in single cells. A prison source described his new accommodation as “a prison within a prison.”

Described as a loner, Mair will be watched 24.7 and his cell will be stripped down and searched to make sure there is nothing in there which he can use to either harm himself or anyone else. His prison clothes are made from material which cannot be torn, which will prevent him from trying to hang himself, if he becomes a suicide risk. Given he has been told he has no chance of ever leaving prison, it is feared he may try to take his own life, rather than face his full punishment.

However, a prison source said that the 53-year-old, who used to work as a gardener will be allowed to work in the unit’s vegetable patch. The men in his unit have a separate exercise area, where there are vegetable and fruit trees.

The Belmarsh insider said: “The trees and the planters have proved a great success in giving those held long-term on the wing a bit of purpose in their life, though they are not allowed access to any tools like pruners or shears.”