Agreed, thanks for changing it. My changeset inherited that relation from previous mappers, so I went along with it, but I'll fix that sort of thing if I see it in future

True. The OSM wiki recommends setting the tags to "highway:track" and "designation=restricted_byway", but this feels clumsy. If you think it's a better alternative than "bridleway", I'll concede.

designation=restricted_byway