Was it a slip of the tongue or a calculated attempt to test the water for a future policy?

London mayor Boris Johnson has said that visitors to national museums should feel "obliged" to pay voluntary admission fees. This was thought by some to signal that a Tory government would reintroduce charges for national museums. But Johnson rapidly back-tracked and insisted that he was committed to free admission.

What he clearly was suggesting, though, was a US-style "voluntary" admission charge, along the lines of the Metropolitan Museum of Art in New York. Its visitors are forced to pass a ticket desk and are asked to pay the full recommended amount of $20 for an adult.

Most national museums in the UK already have donation boxes, with suggested amounts varying from £1 to £4. The income generated from these donations is not insubstantial - the British Museum netted £330,000 last year and the National Gallery took £420,000. But should they be asking for more and doing it more forcibly?

The US model is interesting. If you have the brass neck, you can get away without paying a dime. But you have to know the system to be able to beat it. So first-time visitors or those not familiar with the concept of "voluntary" charges are most likely to pay the full whack, and the most likely to be put off by the amount involved and the strong-arm tactics used to wring it out of visitors.

The mayor also suggested that a voluntary fee might make visitors value the experience more. This idea is currency among those who secretly detest free admission because it leads to galleries being jammed with undesirables who don't really appreciate the experience, while the aficionados can't see the stuff properly.

This concept is flawed. You don't have to pay for something to value it. (And by the way Boris, we do pay for national museums - it's called taxes.)

Free admission has done a lot to boost participation at national museums; resurrecting barriers, whether voluntary or otherwise, would be a backwards step.

Sharon Heal, editor

sharon@museumsassociation.org