Britain's highest earners came under renewed scrutiny from parliament this week as the Commons' Treasury committee completed its grilling of private equity chiefs and Alistair Darling used an FT interview to rule out precipitate action to curb their tax perks. But none was subjected to the fiendish weapon sprung on their counterparts 75 years ago: abundant tact.

Modern unease over the behaviour of private equity partners paying tax at 10 per cent or less is as nothing compared with the discomfiture of the Inland Revenue when faced with a previous generation of the super-rich using underhand methods to avoid paying their dues.