The likely lad

But the fresh-faced 30-year-old admits he is on a learning curve. "I'm still at the listening stage in my tenure," he explains. "My involvement with Building Regulations, planning and construction in general has been quite, er, short and not particularly in-depth."

Not that this is a problem. His entourage includes Paul Everall, divisional director of the Building Regulations, and his acoustic adviser. The two men are squeezed next to the minister's assistant on a sofa in his office on the sixth floor of Eland House. Leslie has positioned himself in a large armchair opposite and from time to time glances anxiously at his mentors for confirmation that his statements are correct. He is already running 10 minutes late and explains he must finish promptly for a meeting with his boss, John Prescott.

It is proving to be a busy term in office for Yorkshire-born Leslie. Less than two months into the post, he has already announced changes to the acoustic regulations. Now, with the publication of the investigation into the collapse of the World Trade Centre, he must decide what changes need to be made to make tall buildings safer. He must also keep a close eye on the controversial self-certification schemes, piloted in April.

The Building Regulations are only part of the portfolio Leslie inherited from Alan Whitehead in May's cabinet reshuffle. His responsibilities also include local government and regional policy, so stint as a Bradford city councillor will no doubt come in useful. He was elected to the council as a 21-year-old politics graduate and three years later found fame as the youngest MP in Labour's 1997 landslide victory.

"There was nobody else Labour in the constituency," he laughs. "So I got selected and found myself squeaking in by a 3000 majority." He fought to hang on to the seat in 2001 by securing funding for projects in his Shipley constituency. His successes include obtaining £116m for new hospital buildings, getting the go-ahead for the £60m Bingley relief road and securing £12.5m for extensions to local schools.

Leslie's claim that he "sort of fell into politics" seems at odds with the ambitious glint in his eye and his rapid promotion to junior minister in the Office of the Deputy Prime Minister after only three years as parliamentary private secretary to Lord Falconer. Described by The Guardian as "one of Labour's most able, young, super-loyal debaters", Leslie has proved himself by steering the fenestration self-assessment scheme, Fensa, on to the statute books after a Tory attempt to scupper the initiative.

I actually do get quite angry about some of the worst environmental issues that I see

Under the Building Regulations there are now self-certification schemes for installers of replacement windows, boilers and plumbing, and there could be more to follow. The schemes enable registered contractors to certify that their work has been completed in accordance with the Building Regulations, without the need to seek building control approval. The minister is a fan of the practice, even though he knows that many small builders say the cost and the red tape involved in joining this plethora of schemes plays into the hands of the industry's cowboys. But he is vague about whether the schemes should be gathered under a single umbrella. "We'll have to keep a watchful eye on it," is all he will say.

Leslie has been more accommodating on the acoustic regulations. After talks with the National House Building Council, the government backed down on the introduction of compulsory testing of sound insulation.

He told parliament on 5 July that he had asked the House Builders Federation to develop a set of approved construction details for separating walls and floors that would provide a consistently good performance. "We wanted to give the industry the opportunity of seeing whether they could develop their own system," is his explanation for the climb-down.

Of more immediate concern to designers is the question of regulatory changes as a result of the collapse of the World Trade Centre towers. But if there are any changes to come, Leslie is not about to let on. "We will have to keep a close watch on what the Americans have learned," he says.

Perched on his armchair, it is hard to imagine Leslie as a Labour radical. What is his big passion in politics? "I actually do get quite angry about some of the worst environmental issues that I see," he says. Ironically, he made headlines weeks before his ministerial appointment for misleading parliament over the use of sustainable timber in the Cabinet Office refurbishment. When Greenpeace activists invaded the Whitehall building to draw attention to the issue, the prime minister branded the occupation as misconceived.

Nine days later, Leslie had to apologise for misleading parliament about the origin of wood used: only the doors and doorframes were from certified sources.