Difficult to say how old it is, although the imperial measure hat size would indicate to me that it isn't that recent. I believe they were also known as the 'Shola Pith.' The trade label looks as though this was aimed at the civilian market rather than military.
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'.
"Knowledge rests not upon truth alone, but upon error also."
Very hard to date this type of helmet, pre circa 1970 is the best I could guess at.
Whatever its just an opinion.