Take a close look at the two chips below. Note that the inlay in the "J" chip is larger than the inlay for the "K" chip. If I had to guess, "J" is USPC and "K" is Burt. I would say the "K" (King's Inn) is 1960s to 1970s, maybe later (or however late Burt made chips before closing). The quality of c&s (including die-cuts) just wasn't there in the later Burt chips. The "K" chip is an example of last generation c&s (including diecuts)