Gaspatch makes a couple of Vickers MG in 1/48 French version and a British Hyland type E. Would the type E be on the M.1C?
Hm, I checked the Windsock Datafile 52, but I haven't found much information about the Vickers.
There were two mount positions, at first upper left and later in the middle. I think for detection of the type you will need to see the end of the Vickers, but there are no pictures known form the cockpit with a visible weapon.
But very clear visible on the pictures are the cooling openings of the gun on the rear of the Vickers.
For my Sopwith Pup I soldered a Vickers from a PE set of "Part" and there are 3 variants for the cooling jacket in the kit, so I would use part 13 (openings at the rear) here for the Bristol:
But a Gaspatch is a lot easier
Cheers,
Frank