JD Wetherspoon has started to employ "spotters" to identify under-age drinkers that have slipped through the net at its pubs.
They are being employed as an extra precaution at around 20 pubs that have failed test-purchase operations.
The move, taken on the advice of "responsible authorities", has been described by Wetherspoon chairman Tim Martin as another piece of regulatory enforcement that chips away at the conviviality of the pub — and creates a confrontational situation between staff and customers.
Wetherspoon faces its first ever possible site closure, pending a review, in Mexborough, near Rotherham, South Yorkshire, which failed two test purchases.
"We have been advised, and have agreed to employ 'spotters' in the event of a failed test purchase.
"Their job is to patrol the floor, seeking those who may be underage (and who virtually never are) in order to ask them to prove their identity," said Martin.
"You don't have to be an ardent civil libertarian to regard this Orwellian development as an invasion of privacy and a waste of money.
"In addition, to the shame of the Government, the authorities and Wetherspoon, legal advice is to regard test-purchase failures as 'gross misconduct', often resulting in disciplinary action as well as a fine from the police.
"Yet another unintended consequence of the entrapment legislation is that those pubs with virtually no underage drinking issues or antisocial behaviour seem to be the ones which are failing the most.
"What logic is there in trying to prevent non-existent problems?"
Legal editor Peter Coulson said it seemed a "disproportionate" suggestion from the authorities because it is not illegal to be in a pub if you are under 18. He also stressed that those aged 16-18 could legally enjoy a pint of beer or cider with a meal when accompanied by adults.
"This is an interesting departure and is a kind of half-way house between doorstaff and due diligence.
"Wetherspoon is caught between a rock and a hard place here.
"If the company fails a test purchase it has to endeavour to act to stop a situation
that could end up in a licence review.
"So they have to head it off and that comes at a cost."