Mark Leftly: How the men from the Mint found themselves in a hole

Westminster Outlook This "virility test" is not confined to the Budget, as corporate executives are increasingly finding out.

Historians joke that Jo Grimond led a 1950s Liberal Party with such a tiny parliamentary caucus that meetings were held in a telephone kiosk. Given that Sir Gerald Nabarro's handlebar moustache could barely fit in so tight a space, it was apt that the wealthy Tory dubbed the Liberals' three MPs as the "shadow of a splinter".

Still, if Sir Gerald is remembered at all, it is for his – even for the age – extreme racism and an acute intolerance of change unbefitting of a self-made man. Mr Grimond, by contrast, performed such miracles in rescuing the Liberals from extinction that the great Scot has a large room named after him in Portcullis House, the MPs' overpriced office building.

Some of the best British political theatre outside the main chamber now takes place in this corner of the parliamentary estate, as was in evidence on Tuesday. Andrew Tyrie, the Treasury Select Committee chairman, prowled the room like a hungry lion as executives from the Royal Mint struggled to answer his blunt questions.

As Mr Tyrie stalked, passing notes and whispering to his committee members, the chief executive and chairman of the millennium-old coin manufacturer were desperately trying to explain it wasn't their fault the Royal Mint had not been privatised.

Ditching the Royal Mint's sell-off was a decision for the Treasury, they argued, and, no, they had not even made a back-of-the-fag-packet calculation of what a privatisation might reap for the taxpayer. They were soon put in their place by Mr Tyrie and his condescending grin for their "lack of interest" in what the business they run might be worth.

Afterwards, I overheard the trio privately protesting that they had been called to the committee to talk about the Royal Mint's annual results, not grilled on what family silver should be in the Coalition's garage sale. They had prepared themselves to explain why the group, ultimately owned by the Treasury, had turned a loss in 2012-13.

They had been ambushed. Royal Mint chairman Peter Warry was cornered into conceding that the Treasury had not asked the business's own executives whether privatisation was appropriate before deciding to keep it in state hands.

The difference with the Budget is that a select committee hearing is an interrogation, not a glorified debating competition: putting someone on the spot in this context works.