In the old days, leisure time used to be something you spent drinking tea with your neighbours. It only lasted 10 minutes back then, as you had to get back to the iron girder works. Today, the iron girder works has closed down and leisure is now a major industry. Enjoying it involves hours of research, hard physical labour, long drives following brown road signs through Lincolnshire and massive expenditure on souvenir wind chimes.

And, while in the past, people wasted away quietly from iron girder worker's toe, now we are diminished by Site Anxiety. Have we taken the kids to the Iron Girder Works Museum yet? No, we haven't. Nor the World of Buttons. Nor the House of Milk Products. Nor the Garden Implements Experience. Shame on us.

It is the conviction of unfettered free enterprise that anything can be a money-spinning tourist attraction. Just because you're not Hampton Court doesn't mean you can't lure people off the motorway and into your visitor centre, where you can flog them inbred local cakes, Welsh love spoons and jumpers knitted from Scottish string.

The recent planning application for a visitor centre by Leyhill Open Prison in Gloucestershire is final proof that Britain has become one vast service industry. The prison has plans to mount an exhibition of agricultural machinery. Presumably, this is because open prisons are where bad farmers are sent (due to claustrophobia), so the guards must confiscate large numbers of agricultural implements as they are smuggled past in the mouths of visiting relatives.

As a tourist attraction, Leyhill Open Prison will appeal to visitors from places where criminals are a novelty, such as Switzerland and Bourton-on- the-Water. It will have a similar appeal to Buckingham Palace, with the same tantalising possibility of glimpsing of an inmate. Afterwards, visitors will buy Welsh love spoons made out of matchsticks and eat slices of hacksaw cake, before slopping out and going home.

Prisons, slate quarries, cheese farms ... the public is proving increasingly willing to suspend its disbelief and pretend it's on holiday. It will be hospitals next, bus garages, morgues and insurance offices.

No closed-down factory is so redundant it can't compete with Westminster Abbey. Scarcely have we said goodbye to the drudgery of the machine-belt economy than we are overcome by nostalgia for it. Back we trudge to the steel yards and slag heaps to see for ourselves just how miserable it really was, and watch former employees re-employed to dress up as former employees to re-enact their former employment. Often they aren't very convincing and have to be replaced by actors, of which the heritage industry employs more than the West End theatre. Ironically, in this artificial age, acting isn't the bad career choice your dad once told you it was, just before he died of iron girder worker's toe.

The day will come when a group of Japanese holiday makers is killed in a Welsh mining accident, or a party of French schoolchildren is caught breaking out of Wormwood Scrubs. None of this will stop the heritage industry mushrooming still further. Soon we will all open our homes to the public, with our own visitor centres in the front garden selling Toby jugs of the wife and T-shirts saying, "I HAVE SEEN THE ROBERTSONS OF CARSHALTON". Then we'll all visit each other's houses all the time, serving each other cups of tea. Just like the old days