Many thanks.
The Hotchkiss was the bipod mount, 3lbs lighter than a Lewis IIRC.
I have carried a Lewis and it is very heavy (well, I thought it was), slung across the back it could possibly be a fairly destabilising weight (but that is my, an amateurs, view).
Just wondered if a modified rifle bucket was used for the Lewis or Hotchkiss.
I have contacted the ALH Association to see if they can throw any light...