We do not believe that the dish involves any of the flower beetles such as Collops nigriceps (illustrated) or Collops vittatus.
A collop is also a thin steak, probably from a lean, tough portion, usually for marinating or layering in a terrine or other concoction. (From M.E. "collope" from Scandinavian, maybe also from escalope.) Minced collops sound a bit like Shawarma.
(And now for something completely different...)
What is really puzzling is Mr Aimsbury's mention of "beccles" as an unspecified but no doubt wholesome lesser-known part of an animal. Beccles is in reality quite a nice little English country town on the Norfolk-Suffolk border, and a cursory search on the word has failed to throw up any other food-related associations... it is, however, famous for an otter sanctuary dedicated to restoring this fine animal to England's rivers and waterways after centuries of depredation. but surely not?
Closer examination of "beccles" reveals them to be 'The small bone buttons placed in bacon sandwiches by unemployed guerrilla dentists.' This is not a definition that can be found in any standard roundworld dictionary. Instead, this definition may be found in "The Meaning of Liff" by that other great English author, Douglas Adams. This reference may be rather obscure for the modern reader - advances in modern mechanised butchery have made the beccle a rare sight.