The book I read to research this post was The SAS 1947 To The Present by Anthony Kemp which is an excellent book which I got from the library. This book is the second in a 2 part series on the SAS and most of the book consists of various true stories about the SAS in action.
There was an incident in northern ireland where a 16 year old lad found a stash of weapons in a churchyard under a headstone. He told his dad who then told the police. Then 2 four man teams were flown in by helicopter and they took it in turns to watch the stash & see if anyone came to collect them. Anyway I assume this lad didn’t know the SAS were there but anyway he returned to have a look at the weapons and according to the SAS he picked up a rifle and pointed it at them so they shot him dead. The forensics couldn’t conclusively prove whether they had shot him from the front as was claimed or shot him with his back turned. It became the only incident where SAS men – the 2 that fired the shots – were tried for murder in a northern ireland court although they were acquitted. The judge did say one of the SAS accused was an unreliable witness. Needless to say the government & the SAS were quite embarrassed by the incident.