Jim Marshall's original premises in Hanwell, West London (courtesy Google Street View.) I think that he later acquired another shop across the road when the business expanded. He actually started off as a drummer and drum teacher and taught a young Mitch Mitchell his chops.
Marshall once had a subsidiary called Park. I think that they knocked out amps and stuff at the more budget end of the market. They've become very collectable in their own right.
I have an old Park fuzz sound pedal which is now worth quite a lot of cash. Don't really know why as the sound of it is pretty shit to my ears, but some people must love 'em.
Just checked on the web. The two knob version (the earlier version that I have) is being snapped up for serious money by collectors. It was badged 'Park' but was actually made for Marshall by Solasound.
From Wiki:Jim Marshall entered into a 15-year distribution deal with British company Rose-Morris during 1965, which gave him the capital to expand his manufacturing operations, though it would prove to be costly. In retrospect, Marshall admitted the Rose-Morris deal was "the biggest mistake I ever made. Rose-Morris hadn't a clue, really. For export, they added 55% onto my price, which pretty much priced us out of the world market for a long time."
The new contract had disenfranchised several of Marshall's former distributors, among them his old friend Johnny Jones. Marshall's contract did not prevent him from building amplifiers outside the company, and so Marshall launched the Park brand name(the maiden name of Jones's wife).
Starting in early 1965, Park produced a number of amplifiers including a 45 watt head. Most of these had Marshall layout and components, though some unusual amplifiers were made, such as a 75 watt keyboard amplifier with KT88 tubes. A 2x12" combo had the option of sending the first channel into the second, probably inspired by Marshall users doing the same trick with a jumper cable.
In 1982, Park came to an end, though Marshall later revived the brand for some transistor amplifiers made in the Far East.