The Value of a Pound?

I recently opened up the cash till to examine its contents and brought
to mind a question about its contents. [I figured that an interesting
way to collect British L/s/d currency would be to put some in an old
British L/s/d cash till.]

I have in front of me pound and 10/- notes from various places around
the world: England, Scotland, Ireland, Gibraltar, Malta, West Africa,
Palestine, New Zealand and Australia (I'm sure there are others, I
just don't have any to hand). Mostly they are from Imperial or early
Commonwealth times.

The question is this: what was the relationship between all those
pounds? Were they all equal to the pound sterling or were there
different valuations? (Obviously, the Scottish pounds are.) Were they
at all interchangeable? - could an English pound be spent anywhere or
could a West African pound be readily exhanged if not spent in
England?

Also, does anyone know why British tills were designed not to fit
British currency? Mine clearly has two slots for notes, but only the
newer (1960s and later) pound notes fit nicely. It is an older
machine, built in 1939, but even the older green and blue quids only
fit if they're folded in half. 10/- notes fit nicely; could it have
been intended to only accept them? Or could this particular machine
have been made for some other market? Probably not, as none of the
other notes fit well either!

Padraic.

la cieurgeourea provoer mal trasfu
ast meiyoer ke 'l andrext ben trasfu.