I have an old 100W Marshall JMP, well old-ish I suppose. It's a 1969/1970, the first year of the metal face plates after the plexi glass face plates.
I bought this amp back in the 90's for £70.
LOUD!!!
I also met Jim twice too, when he used to have the Marshall road show that toured around the country in the late 80's to demonstrate the new products. Thats one of my true 'claim to fame' stories.