The glee with which Tory leadership rivals are competing to deliver the biggest tax cuts reminds me of that great Irving Berlin show song, “Anything You Can Do, I Can Do Better”.

Do you remember the one? Written for the Broadway musical, Annie Get Your Gun, the song is a duet between Frankie and Annie – in which the two boast about how they can do just about every task better than the other, with the memorable line: “Anything you can do, I can do better; I can do anything better than you.”

The latest Conservative hopeful to claim he can do better than anyone is Nadhim Zahawi, the new Chancellor, who, when launching his personal campaign on Monday to become PM, called for income tax to be cut by a penny next year and to 18p from 2024, in what would amount to a taxpayer saving of £12bn a year.