Maelstrom racing in 750mc

Had rather an unusual day today…out of the Blue a lady has called asking if I’d look at her sadly deceased husbands Motorsport bits and bobs.

In the midst of some tumbled down buildings I’ve found a Westfield looking special with 750mc stickers, but more interestingly something called a Maelstrom?

Has anyone a clue as to its history at all? I currently can’t access it due to said fallen down building, but it looks fascinating.