The court was told that he returned to Britain in a hurry after two friends were killed in Iraq, leaving his equipment — including the pistol — to be packed up by colleagues.
It accepted evidence from expert witnesses that he suffered severe memory loss due to a brain injury.
Judge Advocate Alistair McGrigor, presiding over the court martial, could have spared the soldier prison by passing a suspended sentence. Instead he handed down the custodial term.
Lt Col Richard Williams, who won a Military Cross in Afghanistan in 2001 and was Sgt Nightingale’s commanding officer in Iraq, said the sentence “clearly needed to be overturned immediately”.
He said: “His military career has been ruined and his wife and children face being evicted from their home — this is a total betrayal of a man who dedicated his life to the service of his country.”
In 2007, Sgt Nightingale was serving in Iraq as a member of Task Force Black, a covert counter-terrorist unit that conducted operations under orders to capture and kill members of al-Qaeda.
He also helped train members of a secret counter-terrorist force called the Apostles. At the end of the training he was presented with the Glock, which he planned to donate to his regiment as a war trophy.
But in November 2007, two of Sgt Nightingale’s closest friends, Sgt John Battersby and Cpl Lee Fitzsimmons, were killed in a helicopter crash. He accompanied both bodies back to Britain and helped arrange the funerals.
In Iraq, his equipment was packed by colleagues, one of whom placed the pistol inside a container that was sent first to the SAS regimental headquarters in Hereford, then to his home where it remained unopened until 2010.
In May, 2010, Sgt Nightingale was living in a house with another soldier close to the regiment’s headquarters when he was posted to Afghanistan at short notice.
During the tour, his housemate’s estranged wife claimed her husband had assaulted her and kept a stash of ammunition in the house. West Mercia Police raided the house and found the Glock, still in its container.
Sgt Nightingale’s court martial did not dispute that the pistol had been a gift. It accepted statements from expert witnesses, including Dr Susan Young, a forensic psychologist also from King’s College, London. She said that he probably had no recollection that he had the gun.
The court also accepted that Sgt Nightingale had suffered severe memory loss. But the judge did not believe that he had no recollection of being in possession of the weapon.
We’re running out countries to flee to, which I guess is the point.