Quoting myself from Mike's FB wall:
Molto interesting! The first ever compensating sousaphone I have seen documented! Never heard rumours of their existence either. Boosey had the original Blaikley patent from 1878. Where British sousaphones normally use valve block from upright tubas (only that the knuckles are straight), then this one has a valve block with a different permutation of parts and alignments compared to the period upright tuba with 3 compensating valves. Solbron was the Boosey bronze alloy for the pistons, usually looking brown when used some time.
Klaus
