LORD Smith of Kelvin has had quite the career.

An accountant by training, he has led numerous private equity businesses, been chairman of everything from BBC Children in Need and the Glasgow 2014 Commonwealth Games Organising Committee to Alliance Trust, the Green Investment Bank and Weir Group, and has served as chancellor of the University of Strathclyde since 2013.

His involvement in the arts has spanned organisations as grand as the British Council and British Association of Friends of Museums and as humble - relatively speaking – as Glasgow’s Kelvingrove and Riverside Museums. And then there are the honours.

An honorary fellow of, among others, the Royal Society of Edinburgh and the Royal Scottish Geographical Society, plain old Robert Smith was given a knighthood in 1999 before Sir Robert became Lord Smith nine years later. He has since picked up an order of the thistle and a companion of honour too.

So it is with some trepidation that I sit down with him in the Green Investment Bank’s Edinburgh board room – at the same enormous table round which the detail of the post-independence-referendum Smith Commission was thrashed out, no less.

I needn’t have worried: there are no airs and graces here.

Much of this is likely down to the influence of Lord Smith’s plain-speaking late mother, who, when a more youthful Robert balked at the prospect of taking on a management role at Royal Bank of Scotland, made the observation that “a rolling stone may gather no moss but a standing stone gets peed on”.

But there’s also the fact that, unlike so many of his counterparts in the upper ranks of the business world, Lord Smith, who grew up in the Maryhill area of Glasgow and attended the selective but publicly funded Allan Glen’s School, was not brought up supping from silver spoons.

That is far from being the case now, with Lord Smith, who owns an island off Scotland and a vineyard in South Africa, being wealthy enough never to have claimed the fees and expenses he is entitled to as a member of the House of Lords.

“I don’t need it. That’s not a very good reason because some people do need it but I’ve got lots of reasons for being down in London from time to time so I don’t charge for fares or expenses,” he says, adding: “I’m not being a Holy Willie about it - I probably don’t attend often enough.”

Yet he has never forgotten his roots - “break me in half and I’ve got Glasgow written all the way through” - which has helped keep him focused on the micro as well as the macro in his business dealings.

“When I was running Deutsche Asset Management we had about 5,000 people scattered from Japan to Los Angeles but there were probably another 20,000 to 30,000 people attached to them,” he explains. “They were sleeping easy knowing I was up on the bridge looking for icebergs; I was going to bed thinking there’s 30,000 people depending on me to make the right decision.”

Making the right decision for the little guy and not just the business has, he says, become easier with age and wealth because “I’m in a fortunate position that I’m old enough that I’m not scrambling about looking for a job”.

“I can be very principled. It’s one thing I can bring to the party,” he adds.

This much is clear from the revolution Lord Smith has led as chairman of Alliance Trust, the 129-year old Dundee investment institution whose future was looking decidedly uncertain just 12 months ago after it fell prey to US activist investor Elliott Advisors.

Having met Elliott’s aggression with equal force, Lord Smith won shareholder backing to instigate a complete overhaul of the trust - and waved goodbye to Elliott, which agreed to sell back its shares, in the process.

“Alliance Trust was cruising along and suddenly Elliott came in,” he says. “That meant it hadn’t been pleasant for a while. Some people were fourth generation investors and they didn’t want any of that.”

The move appears to be paying off, with Alliance Trust, which had been a serial underperformer, outpacing its benchmark index in the first six months of this year.

Of course, over such a short timeframe that could all be down to the luck of the markets, which in itself would be apt given the role Lord Smith says luck - being in the right place at right time - has played in his career.

Such as the time when being appointed to the board of Sussex Heritage Trust “because I could add up” led to him becoming chair of the National Museums of Scotland thanks to a chance meeting with Brian Lang, the now-former principal of St Andrews University who at that time was involved in a number of cultural institutions.

“We got really drunk together - we had our arms round each other swearing allegiance - then I went my way,” Lord Smith recalls. “Up in Scotland I got a phone call from him saying Malcolm Rifkind was setting up an advisory board under Lord Bute to talk about bringing the boards of trusts of different museums onto one board of trustees. Rifkind said he wouldn’t approve it until they found the name of someone he hadn’t heard of and who was under the age of 90.

“Brian put me in front of Rifkind, who said ‘who?’, and I became a founding trustee of the National Museums under Lord Bute. When he died I became chair. The Museum of Scotland finished on time and on budget and I got a knighthood in 1999.”

Which, in itself, explains the lengthy CV but also why Lord Smith has done his bit for promoting diversity too.

Because you may not think it to look at him - an ageing white male in an expensively tailored suit with prime ministers, chancellors and bank governors in his contacts book - but Lord Smith in many ways epitomises everything the social mobility movement stands for.