I don't see a picture of the water table or the locks. I have a WR droplock made in 1928. The Birmingham proofs are on the barrels and not the flats like the gun you are looking at. I was told this is not unusual for Birmingham guns. The flats are clean with no markings other than the US importer. The locks have the guns serial # and are marked with L and R in gold. This is a number 2 gun so the locks also have a gold 2 on them. The lock serial # is underneath the ejector kicker and you have to move the kicker to see the serial #. The locks and water table are also marked with the patent use number.
The gun you are looking at looks in good condition and has the features (scroll back, WR dolls head, engraving) of their higher end droplock. I'm not a big fan of Brit single triggers and don't know how reliable the WR trigger is. Although, WR put them on their heavy DRs and some famous hunters didn't complain. It is probably solid as long as no one has tinkered with it.
This an old thread on WR droplocks with a lot opinions.
Droplock Ken