The Tory minister for small businesses was unable to say the price of a pint of milk in a TV interview.
Paul Scully was instantly able to recall the rise in the minimum wage for over-23s, from £8.91 an hour to £9.50 in April.
But quizzed by Sky News he replied: “I don’t buy my milk in pints these days, I tend to buy the four pint, erm, larger, larger, erm, cartons.”
The ‘pint of milk’ test is often used on politicians and many have fallen foul of it before.
Chancellor Rishi Sunak suggested a tin of beans cost 50p, only to be told it cost 95p, in an October interview. Tesco charge 55p for one pint of semi-skimmed milk.
Critics say such questions are more about a pop quiz than proper policy - and Mr Scully insisted: “It’s not about what I buy as part of a larger shop.”
But Sky News presenter Samantha Washington told him: “It’s about demonstrating you are a government that understands the cost of living and the pressures on people’s budgets.”

Mr Scully gave a long answer - but could not name the price of a pint of milk, or of his four-pint preferred carton.
He said: “What it’s about is it’s about making sure we have a massive pandemic, as you unwind that pandemic you get into the global situations of supply chains, of energy costs affecting not just people in Britain but people around the world.
“We’ve got to make sure we look after people in this country, what we’re doing is we’re targeting in particular the lowest paid.”
The Prime Minister is set to hold meetings next week ahead of February 7, when Ofgem will announce an April rise in energy bills.
Experts predict it could announce the current £1,277-a-year price cap on standard tariffs will soar by £600 or £700 in one burst, forcing many to choose between heating and eating.

A government spokesperson said: “Ministers are working with the regulator and suppliers to explore potential mitigations so we can protect consumers from high energy costs.”
Energy firms are asking for help to spread April’s cost across multiple years with funding from banks, guarantees or taxpayers worth up to £20billion.
The £140-a-year Warm Home Discount can be extended, but it would likely only kick in next winter, leaving no immediate help.
Green levies could be removed from bills, but it’d leave the Treasury with a black hole and harm Net Zero ambitions.
And while Labour and the Mirror are calling for VAT on bills to be axed, Boris Johnson claims it would be a “blunt instrument” not targeted at the poorest.
At Prime Minister’s Questions, Labour’s deputy leader Angela Rayner warned an “iceberg” is heading for poor families, and most agree something must be done.
A No10 spokesman said: “I’m not going to get into internal discussions. We’re listening to businesses and consumers for how we abate the costs of energy and that work is ongoing.”