Mr Matheson, 59, who stepped down in March as executive chairman of wealth manager Brewin, is still on the boards of STV and Scottish Financial Enterprise, and has accepted a significant voluntary role in Scotland that is still under wraps but which he says "is not a matter of choice but is so important it simply needs done".
Meanwhile, talking at Brewin's St Vincent Street base where he still has an office, the personable Glaswegian said: "It was pretty much 24/7, and I have worked for 40 years non-stop, and away from home ... it's nice to have time to myself for doing stuff that I haven't done before. Thus far my wife [Angela] seems reasonably happy to see a little more of me."
The son of a partner in Glasgow's stockbroking firm of Parsons, he was educated at Loretto School in Edinburgh then joined Parsons "licking stamps in the post-room".
But an early secondment to the City over two years laid the foundations for his career.
"It gave me an invaluable education and insight that had a bearing on the rest of my 40 years in the City."
As 'big bang' drove a wave of consolidation in the broking sector, Parsons was swallowed by Allied Provincial which disappeared into Greig Middleton, and in 1996 Mr Matheson led a well-regarded team of analysts - and blue-chip clients - across St Vincent Street to Bell Lawrie.
This Scottish broker was now part of ambitious Brewin Dolphin, which had floated on the stock exchange two years earlier and went on to snap up three more English regional brokers under chief executive John Hall. In 2005 at the age of 51 Mr Matheson was catapulted into the top job as executive chairman, succeeding both Mr Hall and the retiring non-executive chairman Fred Holliday, heading a business with 100,000 clients, 35 offices and £15 billion under management.
Suddenly, the head of corporate and institutional broking in Glasgow was on the other side of the table, as a quoted company chairman in London.
"While there were some testing days in the following eight years, never once did I not feel I was extraordinarily privileged to be given the chance to be chairman of the group," Mr Matheson said.
"It was quite a thrill when I was told the board wanted me to do it, I was about as astonished as anybody."
He did not abandon his home near Dunlop in Ayrshire and looked no further for his London address than the Royal Thames Yacht Club in Knightsbridge.
"I was around the country a lot, and it allowed me to carry on being chairman right into the evening without a huge personal upheaval."
On being well-liked internally and known for his open door, he commented: "I believe it is very important to be accessible ... it is very easy to lose sight of the importance of people in the business environment but one ignores them at one's peril."
Mr Matheson outlawed use of the term back office at Brewin's. "It potentially belittled an extremely complex area that was a material part of client service and that has become increasingly the case."
The big test was the financial meltdown. "It would have been easy to panic ... market values had an impact on funds under management and fees, but at the same time there was actually a remarkably strong move into the gilt market, where cash had hitherto been lying in banks, and within a matter of months into equities particularly blue-chip and high-yield.
"So actually while it didn't feel all that comfortable at the time it didn't do us any major harm."
When the chairman bowed out, funds under management were up at £26bn, and the group's market value had doubled since 2005 to £500 million.
On comparisons with faster growth at rivals Hargreaves Lansdown or Rathbones, he said: "We had among the highest funds under management in the peer group, we achieved wider national coverage than most operations, I don't think we were behind the curve at all."
Managing regulation was amongst the more testing parts of the job, he said, adding: "I enjoyed talking to analysts and shareholders, in many cases I had known them for quite a long time but in a different guise - undoubtedly it would have been easier for me than it might have been for others."
Media relations came more naturally to the man who had been a sector analyst and dealmaker.
Mr Matheson became a non-executive director at Scottish Radio Holdings after advising on the plc's acquisition spree which saw it own 30 radio stations and 45 newspapers when bought by Emap.
The English buyer had controversially acquired its 28% stake from SRH's neighbour STV (then SMG), but on whether STV and SRH could have forged a strong Scottish media group, Mr Matheson said bigger forces would have militated against it.
"There was a major downturn in the media sector just round the corner, partly market-driven and partly technology-driven ... but I still think there is a great business environment out there for media."
The industry he grew up in has disappeared from Glasgow's financial landscape, and the companies he followed as an analyst typically lost to Scottish ownership, while the big Scottish banks are now controlled to a large extent outwith Scotland, he says. But, he goes on: "It would be misleading to think there are no Scottish-headquartered companies and it's terminal decline, because we don't see the little ones growing until suddenly they are there.
"There are still some very serious companies headquartered in Scotland."
Mr Matheson may well spend more time on his hobby - he has restored Edward Heath's former yacht Morning Cloud and says he may race her again but he added: "I certainly intend to be in London a fair bit in future. I would like not to disappear from the business scene.
"I enjoy STV enormously and if the right opportunities came up I would certainly be interested in doing other things."