Well,

The Woodward "Automatic" is a .450/.400 BPE. No indication of nitro proof present.

The date on the Purdey is wrong. (It might not have been sold until 1920, and thus may appear in the day book at that time, but it wasn't built then). Can't read all the of powder charge line, but it looks like "80grs. Cordite"? With 480 grain bullet, that makes it a .450 No. 2 Nitro Express, NOT a .500/.450. This rifle was full nitro proved BEFORE 1904. The "GRS" and "BULLET MAX'M" marks were discontinued under the 1904 rules of proof.

Both .303s show proof for 38 grains Rifleite, as expected. That was the rule for .303s at the time.

"Serious rifles have two barrels, everything else just burns gunpowder."