Royal Marine Alexander Blackman – better known as ‘Marine A’ – will be released from jail tonight, weeks after having his murder conviction overturned.

Blackman will be reunited with his wife, Claire, after being whisked away from Erlestoke jail in Wiltshire in the early hours of the morning. Military police are expected to transport him out of the jail in a car to prevent the media capturing images of the moment he tastes freedom.

Spy novelist Frederick Forsyth, who took a leading role in championing Blackman’s appeal, said the circumstances of his release sounded more bizarre than fiction.

“The establishment wants to spirit him out in the middle of the night to a secret location. If I wrote this in a book people would say that’s just not the way things are done in Britain. But it is these days,” Forsyth told The Guardian.

The public flocked to support the Marine after he was convicted of murder in 2013 for shooting dead an injured Taliban fighter in Afghanistan in 2011 during his fifth tour of duty.

Daily Mail readers raised £810,000 to pay for a fresh appeal against the conviction, which led to five Appeal Court judges accepting that he had been suffering from combat stress at the time of the incident.

His conviction was duly reduced from murder to manslaughter on the basis of diminished responsibility and his initial 16-year sentence reduced to seven, of which he has already served half, leading to his release on Thursday night.

In addition, Sgt Blackman’s dismissal “with disgrace” from the Marines has been amended to a dismissal, and he will retain his military pension.

He is said to have spent the final few weeks of his time in jail planning his future – and handing over the running of the prison library, where he worked. He has reportedly already received offers of security work and is considering writing a book on his experiences.

Fellow former Marine John Davies, another key figure in his fight to appeal the murder conviction, wrote on the Justice for Marine A Facebook page “Al is not home yet but will be soon. There is no conspiracy or people delaying his release on purpose. Al will serve what is required no more … no less.

“Although everybody is frustrated both Al and Claire are absolutely delighted as they can now plan for their future together … As soon as he is released I will of course let everyone know.”

Sgt Blackman’s legal team praised his wife, Claire, 45, who they called a “lioness”.

Jonathan Goldberg QC said it was down to her tenacity that her husband will walk free today, The Sun has reported.

He declared: “The lioness of this story, who inspired us throughout, is Claire Blackman.

“We [the legal team] had the honour of giving the roar but she is the lioness. She kept the flame alive when the legal system had completely abandoned her husband.

“Her courage and her dignity have been amazing.”