The crown makes me think this hallmark is from Sheffield and the letter looks like that for 1773. However the cartouche looks wrong and I would expect the first year of Sheffield to be quite unusual (it is not 1973!). As very worn, I'm at a loss to know exactly what is the hallmark. Will someone put me out of my misery and give me an expert view? Thanks.
If of any relevance, the goblet is 6 inches high, weighs 186g and has a mark (I think stamped) under the base that reads G 71