Please excuse my ignorance - but is it not a mess collar missing its black felt? I take your point about a potential missing bugle though and of course if you have it in your hand you will see more than the viewer of an image.
All the best
Mike
This site is helpful:
https://rmhistorical.com/
This link (collar badges tab) hopefully shows with and without bugle horn, - removal of bugle possibly an adaptation? post RMLI / RMA merger
https://rmhistorical.com/files/conte...r%20Badges.pdf