Hello,
@Darkman Is it possible to post some more side photos with the fuze? I think it`s not a standard No.80 but rather reworked into something else. I noticed the flange on your fuse does not have the lip that is usually visible on No. 80`s and it also has a notch (at 8 o` clock in your photo) that i can`t see on other No. 80`s.
@Hoeksel is correct to point out that the back-to-back RR`s are a Romanian artillery acceptance stamp used circa 1900-1917. However, the only british gun in use by the Romanian Army during ww1 were a bunch of old 5 inch howitzers, which, as far as i know, do not use No. 80 fuzes. Another british gun was the 4.5 inch howitzer, introduced in service in 1918, but those (and their ammunition) were captured from the Russians, they were not part of a government contract, so we should not expect such markings for them.
So it`s either a coincidence, or something very interesting

We will be able to tell more once you post some more photos of it.