Right. The .303 rifles were handled differently, and not always consistently. For instance, I recently bought a Purdey .303 completed in 1897 that is marked "46.3 grains Rifleite" which is another standard pre-1904 .303 nitro proof.

Under the rules of 1904 the Birmingham Proof House discontinued the use of the two marks shown on my .303 Westley:

The mark used from 1904 to 1954 is this one:

Here's a full shot of the flats of my Webley & Scott .303 that dates to 1937-38 (reflecting the rules of 1925):

With the rules of 1954 Birmingham began using the "Crown over BNP" mark that is still in use today.

But I suppose we have gone far afield from the topic at hand, which is Huvius' spectacular Fraser single shot. Sorry for the digression.

Curl

edit:

P.S. I think the mark 470Evans referred to is called the "Scimitar over NP" (used by London Proof House only):