I took four children to the museum over Christmas. Including admission to a temporary exhibition - the Science of Sport - it cost nearly pound;30. Then there were the fares, the sandwiches and drinks without which an outing of this kind cannot be sustained and there is no change from pound;50. “So what?” you may say. Middle-class mums can afford to cherish their pampered little darlings at the holiday season. But is this what our great national museums are for?

When the Kensington museums were established, to “improve” the understandings of the artisan class in the 1880s, it was never envisaged that admission prices would keep them out. And now, 10 years since a policy of charging gained ground, it is surely time to ask about the consequences of levying these charges.

Neil Cossons, director of the Science Museum and pioneer of admission charging at the National Maritime Museum, has said that he does not believe the entrance figures for the Science Museum before the introduction of charging. The figures are “simply not believable” as the museum “cannot accommodate” 7,000 visitors a day in its galleries.

I am here to tell him this is wrong.

The last time I went to the Science Museum in those far-off days of 1987 it was heaving. You had to wait for every turn at the interactive exhibits of the launch pad and there were queues even to look at the steam engines and computer exhibits.

It was not, I cannot lie, comfortable, but it was exhilarating, not least because of the large numbers of unaccompanied children racing and tumbling in unimpressed mode about the galleries. But sometimes you did see in action the very thing for which we should demand free admission: you would see a child stop and stare at an aeroplane engine or a quadrant. Above all, there was this sense that the whole place belonged to everybody.

It is quite different nowadays. It is true that the museum offers free entry to school parties, under-fives and the unemployed, but adults must pay pound;5.95, and children pound;3.20. and the whole ethos has changed.

Most of the voices I heard were American or Japanese. The only children who were semi-unaccompanied were a large party of American teenagers. They were the ones pushing to the front at the demonstration of water-bottle flight though they were surely too old to need a “go”.

It was the same story, only more so, in the Science of Sport exhibition. Here, even fewer people were queuing to sample such delights as electronic volleyball, where the “ball” is a blip which can be belted back and forth by the back-projected shadows of participants; cod football, where you get four kicks into a small-size goal; or machine-served tennis.

There was a small amount of information in the exhibition - weightlifters need more calories than swimmers, for instance, or why different shoes are good for different sports. But in general, it was a chance for manufacturers to advertise their yummy sports gear through sponsorship and for bored tourists to dabble in virtual physical exercise. Nothing wrong with that and perfectly good fun, but why was it going on in the Science Museum?

It is, though you would be hard pressed to guess it, still in fact our Science Museum, supported by our taxes. Yet its core business - that of presenting to our eyes and interpreting for our minds the great scientific achievements of our country and species - is marginalised. Why support it at all, when Kodak is willing to step into the breach?

On the way out, we went through the exhibit on manned flights into space, complete with real rockets, real spacesuits and real moon rocks. “But, it’s so interesting!” cried my little crew. “I didn’t know the museum had all this real stuff!” We had been so busy “getting our money’s worth” and “having goes” that we had simple drifted past the actual collections.

My fault, no doubt, but a consequence, I suggest, of a museum marketing and presenting itself as a fun theme park and neglecting its role as mass educator. Once you charge admission, you become a hostage to the market and its whims: I would never have accepted the chaos of years gone by if I had paid for it.

But something else, more precious, I contend, is lost. Poor people cannot afford to go.

Do we believe in universal education, or not?

Victoria Neumark is a freelance journalist