A quid.

I haven't seen one of these for years.

This may dismay many of you (myself included) who have done the "but this is legal tender" line in an English pub/shop/supermarket after having a Scottish tenner refused, but it's not. The Scottish 'pound' was based on just that, the weight of ancient coinage. Only the English based their currency on Sterling. We weren't talking to them at the time and never properly adopted it apparently. The banks just started printing 'Sterling' on the notes. Bloody Scots, always causing trouble.

EDIT: This is according to my mate Oli, who's English. So don't flame me...