So Prince Charles thinks farmers are more victimised than blacks or gays.
Well, he might not have said that if he'd read last week's cover story about Najjif Shah, the site worker taunted by accusations of being a spy for Osama Bin Laden. We follow that odious tale this week by examining why the industry is struggling to confront racism, and – as a result – to create a more ethnically diverse workforce. On 9 October, the Construction Industry Training Board will launch a study at a Respect for People conference revealing that the proportion of black and Asian workers has barely risen above 1.9% since their under-representation was revealed in 1999. And everyone from Brian Wilson down realises that construction won't hit its target of 300,000 recruits by 2006 if it shuns a group comprising 7% of the working population.

There is some dispute about the figures. Stef Stefanou of John Doyle says, in his experience, the proportion is far higher than 2%. He may be right, but there are other statistics, too.

For example, 10% of those taking construction degrees are from minorities, but 4% make it into management. To paraphrase Sir Michael Latham, the industry does not resemble modern Britain.

The challenge for construction is immense. To begin with, there's no hope of attracting black or Asian workers while the smell of racism hangs in the air. Some argued that Building ought not to have splashed Shah's story last week, because it suggested that racism was commonplace. Actually, the reverse is true. It was news precisely because Shah's treatment was so rare; most workers are tolerant. But construction is part of a wider society that is, to an extent, racist – as was highlighted this week by a survey in which 25% of Scots admitted that they were prejudiced. All firms can do is be vigilant, coach staff on race awareness and banish the guilty.

That said, racism does not explain why so few people from minorities take up careers in construction. One might equally ask why so few Asians play professional football. But whereas soccer clubs aren't short of talent, construction is. It's the industry's responsibility to redress the imbalance. The forthcoming CITB report is likely to make some positive suggestions, such as incorporating at least one member of an ethnic minority on interview panels. Firms might also follow the CITB's example of marketing the industry in mosques or community centres.

Clients have an important responsibility, too. If the industry's big spenders followed the example of housing associations, and required their suppliers to state the ethnic diversity of their workforce, it would make directors think. Judging by the responses of one or two leading contractors, it's not a question they are asked that often.

Above all, though, the industry needs role models. By coincidence, our teenage supplement Sitelife, published this week, has black architect David Adjaye on the cover. Adjaye is there because he's one of the most talented young designers around, not because he's black. But if his image sends a positive message about the industry to schools, all well and good. What's needed is for Adjaye, and one or two others from the eclectic range of youngsters in Sitelife, to rise to the top. We'll really know that the industry is diverse when the head of Amec is Asian and the head of Barratt is black.