As you can see from the photos the entire cartridge is chromed, there is no head stamp, the cap chamber has an anvil but no fire holes and it’s painted red.
I thought it was a Mk VI* but the photo in Edwards’ book shows neck indents while mine seems to be a coned neck crimp. You can just make out the cannelure.
I also thought it might be a Mk VII or 10 but Edwards’ book shows the bullets should not be chromed.
Is there enough information to make a firm id?