The most horrible moment of my working life was when I was employed on a trading floor and one day got into such a muddle that instead of buying $10m I sold them instead.

The chief foreign exchange dealer – a nasty piece of work if ever there was one – shouted at me, the whole trading room stared and I ran off to the ladies loo and wept. The shame of it all: to lose so much money by being so stupid was bone-crushingly wretched.