hello, I think this is a sheffield cup. It has hallmarks - crown, B, lion, head. It also has the initials JKB, with TH below, and GW below that. It has some initials inscribed on it. Thinking of selling, so would like an idea on price. Thanks.
The hallmark is Sheffield 1869 and the makers are Hawksworth, Eyre & Co.
Assuming your cup (or mug) is a half-pint size I see that similar sized ones are selling on eBay for 100-200 GBP, with some making a bit more than that.
Thankyou.