Information from Mike Carrick, who owns an example similar to the VHS item:

"I have a summary of the British Ordnance list of Changes, and the Mk 1 percussion model (fuse igniter) was introduced 16 October 1877. Unfortunately there is no photo, but the description seems to match the VHS gun. The Mk 1 used a musket cap, had a belt hook, was brass with plain walnut grips and lanyard ring... The description says they stuck the fuse right into the barrel."

Mike has sent an inquiry to friends in the UK asking them to check the pattern room for examples or photos.

The article in CJAC covers only the later cartridge models of fuse igniter.

I expect Mike will post the rest of the information when he hears back from the UK.