Boosey and Co
Boosey and Hawkes
Dearman (!)
Dearman did not make any of their own horns. They're all stencils.
The stamp on these horns reads, "Hessy's LTD., 8-20 Manchester St., Liverpool, Foreign."

Quoting: "Frank Hessy's Music Store was first situated in Manchester Street, Liverpool - Circa 1930 - but later moved to 62 Staley Street, Liverpool. The Store was managed by Frank Hessey assisted by Jim Gretty who sold Beatle John Lennon his first adequate acoustic guitar in 1957." I've also seen this factoid reported elsewhere, so it's probably true.

The question really is, "Who made these?" I don't know, yet, but there are a lot of possibilities. It's definitely not English.

F Besson
Grafton Acrylic Alto
Grafton Acrylic Alto
There's a nice take-apart of one of these at Barnard Music.
Hawkes and Son