Haven't had or used one for a while and this lovely tin, a recent find, brought them back into mind. A Berwick Cockle has no association with the sea though! It's a humbug or mint ball - I've never had one, so can't comment on what they taste like. Great tin though.
Talking of cockles, take a look at this film "The Cockle Man" by father and son film makers Matt and Mark Daunt. It tells the tale of Dave Bartram who trawls the pubs of Nottingham selling his cockles from his basket. Could do with a Dave in the pubs around here. Super stuff.