A new £20 note, with enhanced security measures and featuring a portrait of Scotsman Adam Smith, comes into circulation today – much to the bafflement of many people who are not aware of the UK investment Smith has made to economic theory.

The note has microlettering and a wider holographic strip to prevent counterfeiting in a bid to deter the forgers who see each new banknote issue as a challenge to their professional abilities.

Bank of England executive director for banking and chief cashier Andrew Bailey said the new security features – representing a significant UK investment in the currency – were the latest step in the “fight to prevent counterfeiting”.

He added: “Maintaining public confidence in our banknotes is paramount.”

The current crop of £20 notes, featuring the English composer Edward Elgar, will be phased out over the coming months.

But the greatest challenge for the person on the street was the identity and achievements of Adam Smith, the Fife-born economist and philosopher well-known in educated circles for his book ‘The Wealth of Nations’, which some say practically invented the idea of competition and market forces.

“Never heard of him,” declared 25-year-old IT manager John Murphy.

“Adam who?” asked a baffled Kate Stimpson, 32, a civil servant. “But, come to think of it, who’s Edward Elgar?”