But even in these areas high lead levels can be detected in children’s blood, and this despite a dramatic drop in airborne lead following the introduction of unleaded petrol.Dr Millstone suggests that lead paint, especially in poor or badly maintained housing, is far more of a risk than has been realised. “Can it be a coincidence,” he asks, “that Glasgow has the most severe inner-city delinquency and vandalism, and also the highest monitored lead levels of any European city?”In hard water regions, such as London and the South-east, limescale build- up inside water pipes cuts down the amount of lead dissolved. It is particularly damaging for children under seven, whose brains and organs are still developing, and for pregnant women, who can pass the poisoning on to the foetus.
Old lead water pipes are the best-known source of lead pollution – the water flowing through the pipes dissolves the lead and delivers it straight to the kitchen tap. He has found startling geographical correlations between high lead absorption and civil disorder. This hazard is most significant in soft water areas such as Glasgow, Edinburgh, Liverpool and Manchester, where high levels of juvenile delinquency have been linked to lead.Ian Parker, a building surveyor who has studied the problem of lead poisoning and buildings, has compared data on lead intake with crime figures.

Apart from causing behavioural problems, lead can damage the brain and central nervous system, the liver, kidneys, bones and blood. “Current research shows that a level of only 10 micrograms per decilitre is causing measurable harm to the mental development of young children,” he says. In his campaign manifesto Dr Millstone says that the “safe” limit set by the British government in 1983, of 25 micrograms of lead per decilitre of blood, is far too high. The campaign’s leader, Dr Erik Millstone, of Sussex University’s Science Policy Research Unit, estimates that around one in 10 British children have lead levels in their blood which are high enough to affect intelligence and cause disruptive and delinquent behaviour. LEAD poisoning from old building materials has hit the headlines once more following the launch of a campaign to reduce domestic lead pollution. They have paid good money to a man who professes to be a building expert but who, it transpires, does not know the first thing about how roofs are put together.

And that, dear reader, is why this column has had to return again to the question of architects. Last week I discussed the problem of trying to find a decent builder … but what about competent architects? Does their professional association monitor their behaviour? Do they have to submit a selection of their work for judgement by their peers? Of course not: once qualified, architects are free to practise unobserved for the rest of their working lives, and the punters, by and large, have to make do with their cock- ups.So, all you architects who write in and tell me I don’t know what I’m talking about, and ask what qualifies me to pass judgement – just think for a minute – are you sure you could pass the purlin test?q You can contact Jeff Howell at the Independent on Sunday or by e-mail: Jeff doctoronthehouse.demon.co.uk. Because the architect, this supposedly learned man, this expert in the ways of all building things, asked if the purlins could not be removed. “Not without the roof falling in, they can’t,” replied the builder. And so it came to pass that the purlins remained in place and the expensive Swedish windows were installed on top of them, and cannot now be opened. So they cannot be cleaned from the inside, and in the summer the solar gain through their huge glazed surfaces will heat the place up to sauna temperature while they remain firmly shut.And the punters have paid for this debacle.

But in general roof windows, unlike dormer windows, can be put into old buildings without planning permission, and architects and interior designers love them because of the way they let in the light.Whatever, the old stable block was set to be given the all-over Swedish look with a rash of huge roof windows. The builder, a conscientious sort, could not fail to notice that several of the roof windows were so big that they would span across the purlins – the big horizontal timbers that support the rafters – so the windows could not be opened.Being conscientious, he pointed this out to the architect, whose response was what led to this story. The builder duly ordered them and they were delivered to the site Then the trouble started. But conservationists don’t like them because you have to lose a chunk of your original roof tiles to insert this very obvious Swedish-look double-glazed panel. And roof windows can also be responsible for solar glare, bouncing the sun’s rays into the eyes of passing motorists – in fact some local councils have banned them for this reason.