IF there is an Edinburgh way to doing business, Keith Miller probably epitomises it. Vastly wealthy, quietly spoken, soberly dressed, discreetly unforthcoming about colleagues, competitors, contacts and money, he seems more like a rather charming investment banker than the boss of Britain’s biggest privately-owned property and construction firm.

Yet Edinburgh-based Miller Group, which he has headed since 1994, is currently on a roll. This month it announced an eleventh successive year of profit growth. The £750m-turnover firm, which built the Skye bridge and is now providing Glasgow with a raft of new schools under the Private Finance Initiative, is among the most respected in Scotland.

Set up as a housebuilder by Miller’s father and uncle in the 1930s, it has been completely overhauled by the present top team and is moving south, itching to do deals to add to the joint ventures it already has going in Europe. If it wasn’t a private firm, we would probably be hearing an awful lot more about it.

Miller wants that put right — profile helps, after all, with the recruitment and retention of talent. So here we are, in his new London office, a fresh investment off Piccadilly, assiduously picking through his latest trading statement.

Miller, 55, who received a CBE in the new year honours list, insists that the family firm is run with all the careful attention to detail of a public company. Statements are made, full results follow, an annual meeting is held. The difference being, of course, that most of those at the meeting are Millers. Last year, the family’s wealth was estimated at £368m.

“We are 92%-owned by various members of the family,” he says in his soft Edinburgh brogue. “The rest is held by employees. There is a savings-related share-option scheme, very tax-efficient, and options for management.”

The decision to let others buy in is a canny Miller compromise. To make it work, the firm’s merchant bank, Noble Grossart, sets a share price once a year, based on earnings and performance relative to its peer group. If that sounds complicated, it is. But for the Miller at the top it solves that age-old problem of family firms: motivating non-family colleagues who never feel a part of it.

The other solution, floating the firm, is frequently mooted but Miller — the last family member left working inside the business — insists that being private gives it unprecedented freedom. Also, the firm doesn’t need the extra capital a float would raise, and its main shareholders don’t need an exit. So the family has found a compromise that works, for now.

“Letting employees buy our shares was a difficult Rubicon to cross,” he smiles. “Lots of private companies won’t do it, but I don’t think there is any right or wrong answer, I just believed culturally, for our company, it was the right thing to do.”

There is a gentle reasonableness to Miller that makes him easy to underestimate. Tall and slim, with the angular good looks of a darkly greying Nigel Havers, he is so smoothly self-effacing that it is hard to remember just how much he has changed the Miller Group.

When he took on the top slot 11 years ago, it had slumped into loss, and had interests in open-cast coalmining, contracting and civil engineering as well as housebuilding and property development. Now it concentrates on housing, construction and property, having sold the loss-makers, and works tightly with the Edinburgh banks that have risen to prominence in the past decade: HBOS and Royal Bank of Scotland.

Hence Miller’s confidence about capital. Both banks pop up as partners in Miller deals and the group will soon move to a new headquarters in a Miller-developed business park next to buildings where HBOS and Royal Bank have a base.

“We know all the bankers at the top level and that’s an advantage,” nods Miller. “They have been great supporters. If we had been in London trying to do banking deals with Barclays and NatWest, I think it would have been hard. But the fact we have been swimming in the same pond in Scotland made it easy.”