A protest is being held today demanding the fair trial of a Stevenage man convicted of triple murder and serving a minimum 35-year jail term.

Along with his brother Miran, Kevan Thakrar of Lomond Way was jailed in 2008 for killing three men over a drug deal, and attempting to kill two women.

Keith Cowell, 52, his son Matthew, 17, and Tony Dulieu, 33, were lined up and shot with a sub-machine gun in Bishop’s Stortford in 2007.

Matthew Cowell’s girlfriend Clare Evans and a second woman, Christine Jennings, were stabbed after the killers ran out of ammunition. Both women, who were targeted because they were witnesses, survived.

Kevan Thakrar has always maintained he was wrongly convicted, and his supporters will be holding a protest today at HM Prison Service headquarters in London asking for a new and fair trial, as well as Thakrar’s immediate release from solitary confinement.

Thakrar’s mum, who did not want to be identified, claims her son is innocent of murder and is suffering from post-traumatic stress disorder.

She says he has been held in a close supervision centre – which holds about 60 men considered to be the most dangerous in the prison system – for six years.

She said: “They continue to hold Kev in isolation. Until Kevan receives treatment for his PTSD it is unlikely he will return to the general population. No qualified therapist has ever been appointed.”

She has shared letters with the Comet written by her son while in prison.

He says he is locked in isolation in a cramped cell for at least 23 hours a day and has suggested prisoners contemplate suicide on a daily basis in order to escape the extreme conditions.

A prison service spokesman said: “Close supervision centres are designed to manage the most disruptive and dangerous men in the prison system and reduce their risk of violence to others.

“In line with the Chief Inspector’s recent report, we are making further improvements to these units, including creating more opportunities for purposeful activity and progression to the mainstream prison population.”

A Facebook page called ‘Justice for Kevan Thakrar’ has amassed 2,230 likes and a petition, directed at Secretary of State for Justice Michael Gove, has so far gained 65 signatures.