These were mostly made in Willenhall, were common in the 19-early20C. Look for the keyhole plate in conservation areas of old towns throughout Britain — though rarely is the latch still present on the door.
They remained popular in Scotland, especially for main (i.e. street) doors of tenement blocks well into the 1980s in poorest areas, gradually being replaced by electric intercoms and door releases.
Early keys were forged blanks, later ones mostly cast.
I saw a display latch on the counter in an ironmonger’s shop in Fleetwood in the 1960s, but it was already so old-fashioned the shopkeeper declined to sell it to me :-(
American tourists like to pay high prices for these keys.
Some of the long keys, especially open at the end, are indeed for arab-made ‘chinese’ padlocks, sliding along in a groove in the bottom of the lock body.
