Please help with identification

Hi, please can you help me identify this on the bottom of a hip flask that belonged to my late uncle? I want to list it on Ebay correctly can’t identify it as silver as I can’t match it with an assay office so I’m assuming it’s silver plate. Any help would be appreciated.
Hip Flask.jpg

The maker’s mark appears to be T(?)W over LTD. Sorry I can’t identify this. The other letters are EPBM for ElectroPlated Britannia Metal - so definitely plated rather than solid.

Thank you for looking your help is appreciated - I’ll now have a mosey and find out what Britannia Metal is. Cheers

It is a white metal alloy similar to pewter.