When is a Biscuit Not a Biscuit?

I was minded earlier of "King Biscuit Time", a long-standing US radio show that has been broadcast daily since 1941, which makes even "The Archers" seem a tad arriviste. It has hosted and featured music by such blues greats as Sonny Boy Williamson, Pinetop Perkins and B.B.King. The 'King Biscuit' of its title refers to the sponsors of the programme, King Biscuit Flour. Now, to a Brit, a biscuit is a thin, crunchy, usually sweetened confection, often taken alongside tea as a compliment to the beverage, and sometimes dunked in said libation. To a North American, however, a biscuit is a kind of cross - to a Brit, anyway - between a scone and a Scotch Roll, to be eaten in savoury contexts such as mopping up gravy. Which wayward thought leads me to the muffin: in the UK, a muffin is a savoury, much like the American biscuit, to be eaten with butter - although often with sweet preserves such as jam - and cheese, Marmite or whatever. To a North American, a muffin is a small, sweet, chocolate or fruit cake. Nowadays, as the world has moved on into a more internationalist sphere of culture and cuisine, all forms  and nomenclatures are now broadly accepted on both sides of the pond. The interesting thing is that [English] muffins, [American] biscuits, and [English] biscuits are all ultimately derived from naval hard tack...