There was a time when the £50 note was paid out as common denominator in any serious money institution, the £20 note was "small change", the tenner was "a joke", and the fiver was "a bad joke".
Silvers were often seen tossed along the pavement, while tuppence coins were trodden upon.
With the financial crisis, the £50 note was spirited out of circulation, replaced by the £20 note-pad. About a year ago, tenners were coughed up at cash-point machines with a rare £20 (providing the bank still had some)

, and now the fiver!
A projection I made last night based on excel spread-sheets and a pie chart (knowledge garnered at Pitman Training while on the dole), showed me that within a few years, cash-points will be spitting out 20p coins, pennies will never be seen lying on the pavement, and for a tenner, people will swim the Channel and back.