Can somebody explain to a numpty(me that is) about buying and returning foreign currency. I exchange some uk sterling this morning at M&S, they sell the US dollar for 1.91(or near as damn it) but buy it for $2.06. So if this is the case could I have just sold them the money back that i`d exchanged and made myself a profit. Sorry if this seem a stupid Q to ask, but I have seen far worse than this one:)
You seem to have got the sums in your head the wrong way round. Look at it this way:
If you hand them �100 and ask them to sell you some US currency, you'll get $191. Now let's say that you change your mind and want your �100 back. They'll say 'OK, that'll be $206 please'. You won't have enough because your money will have effectively been devalued by their profit.
Teash, Chris is right. That's how exchange agencies make their money.
Put it the other way; you have 100$ in your purse, they buy at $2.06 so they give you �48.54. if you want to exchange your �48.54 for dollars they'll sell at 1.91$ so you get 92.71$. Result you lost over 7$ in the deal.