I wonder if the new plastic notes will be teflon coated to repel faecal matter, unlike the present paper notes (and cards) that are covered in poo http://www.qmul.ac.uk/media/news/items/se/85711.html

remember to wash your hands!

<i>Don't the US equivalents, and if not, why not?</i>

Coins are pretty readily distinguishable. Even the dollar coin that some complain about being the same size as the quarter lacks ridges on the side to make it easy to identify. Bills, though, are all the same size for now. I think it is mostly tradition and inertia that keeps them so.

<i>You do realise it's all a fiendish plot to get you to spend them or give them away as soon as possible?</i>

Speaking of plots... The primary lobbying group advocating for dollar coins in the US is a grab-bag of mining and vending machine companies.

"if a hundredweight of coal costs one pound, sixteen and three pence three farthings, how much would it cost to fill my cellar that holds six tons..?"

£217/17/6d

You can do it on a modern calculator. If you shout at it enough

<i>And Heimdall obliges in short order!</i>

Indeed I did! The currencies of western and northern Europe, Canada, and Australia are more relevant to the US than India, for example, where the annual median per capita income is $616. No wonder they have small denomination bank notes!

Well as a practical matter if bringing unused British pounds home for future trips try to get the newer plastic ones and not the old cotton ones as IME you will then later have to go to a bank to exchange the old notes for newer ones - not like the U S of A where a greenback no matter how old or when made is valid currency that everyone has to accept as valid currency.

British currency can be made redundant - this has happened several times before when bank notes were redesigned.