Geno:
I could only offer a wild guess. Such rifles in British calibers are common, so comps are readily available. For British doubles in comparable European calibers, I know of none.
Doesn't sound like this cartridge (10.75/44 Cordite, 346 grain bullet) is greatly different from the .375 No. 2 2.5" Flanged (40 Cordite/320 grain bullet), or say, a .450 Nitro for Black. Roughly the same power level, suitable for the same range of game. I think it was probably ordered by a European for use on driven game, deer and boar. Kinda fits the straight hand. The fact that the cartridge is not British though would, I think, be a detriment of value in comparison to similar rifles chambered in comparable British cartridges in this country. Nice British doubles in .375 2 1/2" Flanged or .450 NFB don't bring what more desirable chamberings do, and I think this one would bring less. Since I know of no comparable sales for a rifle like this, I'm really kinda poking around in the dark. A Westley boxlock in .375 2.5", say $12-14k. This one, maybe $8-10k if the bores are nice, less if brass availability is a serious problem. By comparison, were it a .450/.400 NE or .450 NE, twice that or more.
Suggest contacting WR for the records. Be sure to include the T prefix, as Westley had a number of tables.
Hope this helps.
