New testimony has emerged over the execution of a Scots Guard for desertion during the Great War.

Private Isaac Reid, of the 2nd Battalion Scots Guards, was shot by comrades in 1915 for desertion following a court martial. Three of the four sergeant majors who had drawn lots for the shooting would die in battle, all on the same day, a month later.

Now testimony from the only survivor of the cast of principal characters has shed light on the episode and put a question mark over the story of a grim sequel.

In a book written in 1919, author Stephen Graham described an incident in which "Private X", dazed by shellfire, was reported as a deserter by "Sergeant Major Y" who has been thought to be Shropshire blacksmith's son James Lawton who died aged 35. On the basis of his testimony, "Private X" [Reid] was shot at dawn by colleagues ordered to form the firing squad.

On Graham's account, "Sergeant Major Y" [Lawton] was a martinet who "through army training, had become the sort of man who presented every fault in the worst possible light". After the execution, he was shunned and when mortally wounded at the Battle of Festubert in May 1915, was refused water by the men.

It has emerged Californian-based David James made a tape recording of his grandfather Alfred James's recollections in 1982. Mr James, then an Acting Company Sergeant Major, was one of the four who had drawn lots.

He does not name Reid and makes no mention of Lawton being shunned, or denied water while dying. It leaves the truth unresolved.