You've got all of these ideas when people are trying to be elected and then they don't follow through

When his company, Clyde Blowers, surpassed the £1 billion turnover mark, the milestone barely registered with the East Kilbride-based businessman.

"You know, I didn't think about that," he admits. "I see it as a journey and it's just a number that I passed. It's going to be a lot bigger than that."

There's nothing sexy about coal-fired plants, dirty power station boilers or waste water. Yet these are the bread and butter of his global operation – an umbrella organisation of around 90 subsidiaries in 30 countries dedicated to providing the logistics, parts and servicing that keep industrial wheels turning.

Famously, his great triumph of last year was selling Clyde Union Pumps for £750m after buying the struggling enterprise for £45m in 2007, saving 600 jobs in the process, the romance of the tale only amplified by the fact that it was where he served his apprenticeship.

His empire grew off the radar at a time when people were distracted by new, cleaner industries of the dot-com boom, property speculation and tertiary services. He bought a 29.9% share in Clyde Blowers in 1992, led a management buy-out to take it private in 1999 and is now chief executive of the seemingly recession-proof company with a £1.4bn turnover and some 6000 employees.

"If you look at the 90s, there was a real focus on retail, property and financial services. Really, manufacturing or engineering just wasn't an attractive place to be at all. I think it's now being realised that you have to have a reasonable manufacturing base. You can't rely on the financial services or the property sector or retail to drive an economy."

The father-of-three makes no secret of his success. The aggressively acquisitive entrepreneur spots small, specialist engineering companies that he can invest in and add value.

Companies involved in the production of energy – oil, gas, electricity and renewables – mining, petrochemicals and waste water form the bulk of his portfolio. He and a team of directors and analysts, backed by the investment fund generated by private equity groups and institutions, have three criteria to fulfill for their acquisitions: does a company provide a "mission critical" service or product; is there a revenue stream to be gleaned from servicing, spare parts and maintenance; and, lastly, is that company a well-respected niche brand, but restricted by its geographical reach.

The key to the third criteria, he says, lies in globalisation, a lesson learned in studying part-time for the second of his two Masters degrees in business. For example, the recent acquisition of a Huddersfield-based company, David Brown, is already bearing fruit after signing a multi-million-pound deal to provide gearbox systems for Samsung's major new offshore wind turbine project in Methil, Fife.

Mr McColl built the capital and business acumen to buy Clyde Blowers through his spell as a "company doctor" in the late 1980s, turning around the fortunes of struggling companies in return for a percentage of their success.

If he can do this for engineering, why hasn't his model been copied by others?

"I think that quite often when I read about businesses. It's a real shame," reflects Mr McColl, who received an OBE in 2001. "We were, particularly in Glasgow, the manufacturing base for a lot of the British Empire back in the 19th and early-20th century. We've lost that. Whilst we would probably have lost some of it, it's a shame that we've lost so much. In many cases it was poor management and poor leadership that allowed that to happen."

Long before the likes of seawater injection pumps entered his thoughts, it was cars that first sparked an interest in engineering. Growing up in the village of Carmunnock on the south side of Glasgow, he would watch neighbours work on their vehicles or potter on the car belonging to his butcher father.

Despite being the dux of Carmunnock primary school, he left Rutherglen Academy at 16 with three out of five O grades. There were only two options for engineering apprenticeships available: Rolls-Royce in East Kilbride or Weir Pumps in Cathcart. "I picked Weir Pumps because there was a bus that went from Carmunnock down to Cathcart, but there wasn't one that went to East Kilbride." Does he think about how it could have been different? "Yeah, I might have ended up in Rolls-Royce and owning Rolls-Royce. Who knows," he chuckles.

The sporty number with the personal registration plate outside his headquarters overlooking the Queensway thoroughfare bears testament to that continued passion, which sees him attend the Abu Dhabi and Monaco grand prix every year.

"I had quite a few nice classic cars," he added. "I like them to be used. I found I was travelling a lot and I'm really tied up with the business just now and wasn't using them. I've sold most of them, but I still have a few."

The office is a stone's throw from one of his homes in Thorntonhall. Of his three grown-up children, his son is an analyst in his private equity firm Clyde Blowers Capital and one daughter continues to work with Clyde Union Pumps, while another daughter owns an equestrian centre and property management company.

The McColl pile in the tax haven of Monaco doesn't escape the attentions of detractors of his cosy relationship with First Minister Alex Salmond. As an economic advisor to the Scottish Government, yet resolutely "apolitical", Mr McColl has been outspoken about his desire for change, not independence.

"I think what we have to do is have a debate about what are the powers that we should have," he said. "I think there has to be full financial powers but still work as part of the UK. And there would be certain things that are done at a UK level, which would be defence, foreign office, pensions perhaps, but all of the tax-raising powers and the control of that would be with the Scottish Parliament."

He travelled to China at the end of 2010 as part of a trade mission led by Prime Minister David Cameron. The rapidly growing middle-classes in the country are creating a fierce demand for the energy and infrastructure that McColl's companies provide."The good thing about China is they work on these five-year plans," he said. "When they make a plan, they do it. They don't make a plan for political reasons. Quite often I feel in this country you've got all of these ideas when people are trying to be elected and then, when they get elected, they don't follow through."

Mr McColl is less forthcoming, though, on the subject of the Blue Knights consortium, which last week announced it would be "stepping back" from buying Rangers Football Club. Despite advising the Rangers Supporters Trust on a potential fan buy-out in 2010, he has neither confirmed nor denied any involvement in current talks for the club.

There's no shortage of requests for his time and money. A cheque for £200,000 earned him the title of the honorary president of the 10-bed Kilbryde Hospice to be built on the grounds of Hairmyres Hospital over the next two years.

As the chairman of Enlight, the Entrepreneurial Exchange's venture philanthropy fund supporting charities that work with young people in Scotland, he wants to see a return on the donations he makes.

Newlands Junior College, meanwhile, has the potential to be Mr McColl's most high-profile venture away from engineering. By this Christmas, he hopes to have an operational school at former Clyde Union Pumps offices in Cathcart that would take disaffected S3 and S4 out of the traditional learning environment.

An initial intake of 30 S3 pupils – followed by another 30 the following year – would be selected from 10 secondaries in the catchment area, with students learning a mix of five academic subjects, life skills and vocational training such as construction, engineering and technology.

"It's not an inferior way to learn. In many ways it might be a superior way to learn," he adds. "My idea is if we can do this and prove the success, and I'm absolutely confident it's going to be a winner, then this could be replicated around Glasgow and other parts of Scotland. We will have the model there."

A generous dose of charisma has played no small part in the career of one of Scotland's richest men. He attributes part of his rise to asking successful business people for advice. All, except one, obliged. A phone call just wasn't good enough.

"I said no, it's OK, I'm sorry I wasted your time. They were back-tracking, saying I'm happy to speak to you, but I've not got time for you to come in and see me. I said that's fine. I don't need to bother you. I didn't."