I am translating The Antiques Roadshow. After reading an inscription from King George IV on a gold pen, one of the experts says: "That's a bit of belter". Could anyone explain to me what this expression means? Thank you!
I think it might come from the slang expression "to belt" to give a hard blow or hit. So a "belter" is something/one that gives you a hard blow. I'm guessing but perhaps the estimate expected for the pen was more or less than they'd imagined, hence it gave then a blow/shock.