Jailed Royal Marine Sergeant Alexander Blackman will find out the result of his appeal this Wednesday. Five judges will announce whether the jailed Royal Marine’s murder conviction is being quashed or upheld.

The panel at the Royal Courts of Justice in London will sit at 10.30am to deliver their long-awaited ruling. It is just over a month since Sgt Blackman’s two-day appeal heard he was suffering from a combat stress disorder when he shot a wounded Taliban fighter in Afghanistan in 2011.

The court heard from three psychiatrists who agreed he had a recognized mental illness when he pulled the trigger. His disorder substantially impaired his ability to form a rational judgment or exercise self-control and this would have affected his ability to know whether the insurgent was alive or not, the experts said.

The prosecution did not contest the psychiatric evidence but argued it was not enough to absolve him of responsibility. Richard Whittam QC, for the Crown, said there was no evidence to the contrary about Blackman having an adjustment disorder but the issue was ‘did it cause what happened?’ He said: ‘One has to assess the breadth of the disorder and the effect it was having.’

Five of Britain’s most senior judges, led by the Lord Chief Justice Lord Thomas, will now give their ruling. Sgt Blackman was convicted in November 2013 by a court martial in Bulford, Wiltshire, and sentenced to life with a minimum term of 10 years, later reduced to eight.

The five judges heard that at the time of the 2011 incident, Sgt Blackman was serving with Plymouth-based 42 Commando in Helmand province in ‘ghastly’ conditions which were a ‘breeding ground’ for mental health problems.

Sgt Blackman’s case was referred to the appeal court by the Criminal Cases Review Commission (CCRC), the independent body that investigates possible miscarriages of justice. If he wins and the conviction is reduced to manslaughter, the issue of what sentence should be imposed will be dealt with at a further hearing.

During his trial, Blackman, who denied murder and was known at that stage as Marine A, said he believed the victim was already dead and he was taking out his anger on a corpse.