Great addition to add to your collection James! If only this helmet could talk, I think it has a high possibilty to have been used during the Northern Ireland troubles back in the early 1970's, it would make a nice display to recreate the soldier on the magazine cover from 1972.
The riot gun the soldier is holding is the US-made FED riot gun. My preferred weapon was the Webley riot gun, with the FED as a spare. I believe that the Webley was a variant of the line-thrower, although I could be wrong.
Books published to date... 'Belfast Diaries: A Gunner In Northern Ireland'... 'A Tough Nut To Crack - Andersonstown'... 'An Accrington Pal: The Diaries of Pte Jack Smallshaw, September 1914 To March 1919'.