When Ewan Brown, chairman of Scottish Financial Enterprise, warned last month of the uncertainties facing an independent Scotland, his 44 years at the heart of Scottish banking assured him of a respectful hearing on all sides.

"A yes vote will bring profound irreversible change to our business environment and it is proper for us to find out as much as we can about what that would mean in practice," the veteran banker told Scotland's annual SFE gathering.

Ahead of next week's Scottish Government white paper on independence, he reiterates: "It would be good if over the next 10 months there was much more focus on what is best for Scotland and much less megaphone communication, yah-boo rhetoric and going for the man rather than the ball."

One plea which did, however, go unheard was Mr Brown's warning in early 2006 to the Financial Services Authority, as chairman of Lloyds TSB's audit committee, that banks' widespread selling of payment protection insurance was storing up a potential regulatory crisis. Neither the bank nor the regulator paid enough attention. His explicit sounding of the alarm, four years before the PPI scandal broke, was revealed earlier this year by former Lloyds risk director Carol Sergeant, who told the Parliamentary Commission on Banking Standards she "wished she had followed the lead of Ewan Brown".

Partner in Scotland's most successful merchant bank Noble Grossart, adviser to its biggest success stories Stagecoach and Wood Group, and chairman of Lloyds TSB Scotland for nine years, the self-effacing Mr Brown (now a youthful 71) had accepted leading roles in education and the arts for 25 years before taking on the unpaid leadership of SFE last year.

The only job he expresses regrets about is his chairmanship of tram developer Transport Initiatives Edinburgh, which he took on for an agreed period before stepping down at the end of 2005. "I wish I had stayed as chairman," he says. "I think I could have recruited a very able chief executive. That's all I'm going to say."

But his banker's discretion - Mr Brown has never knowingly given an interview - has never prevented the Edinburgh-bred kirk elder from championing ethics and good conduct in business. He traces it to the apprenticeship at Peat Marwick Mitchell in the late 1960s under senior partner and mentor George Dewar. "I was left in no doubt at all what was right and what was wrong from the point of view of professional conduct, and you were expected to take that into your own professional affairs too - your tax and so on.

"That has changed hugely. Accounting firms don't have wise old owls, people move on in their 50s, people make careers on boards. Moneymaking has taken over from professional standards."

Mr Brown says that culture change has affected all of business but most obviously the financial sector. "It will take possibly a generation to change that...very slowly."

On the sales culture at Lloyds during his nine years on the board, seven as audit committee chairman, Mr Brown says: "Lloyds was a terrific bank."

But none of the banks, he explains, was prepared to charge for current account banking and move away from add-on selling. "Eric Daniels at the top of the bank took this very seriously, he was very conscious of treating customers fairly. I see it as quite similar to MPs' salaries and a lot of other things happening in that period when things were going to excess - MPs' salaries were too low, banking products were relatively unprofitable."

Joining the newly-founded Noble Grossart in 1969 as its first recruit, the young banker grew his own reputation along with the bank's, and came to hold 22% of the shares. "The way it worked is I worked with Angus not for Angus," he says. "We were able to make the best of each other's skills. I probably led on North Sea oil, on Pict Petroleum which I effectively managed for a number of years, and that led me to the relationship with Ian Wood, and probably helped develop the relationship with Brian Souter, relationships which have endured over a very long period of time - and two of our most successful investments. The fact I was able to do that independently of Angus has helped us to cohabit over 43 years."

Mr Brown became a non-executive at both Wood Group and Stagecoach, and still sits on the transport group board as an independent director after 25 years. He comments: "I think I am as independent as I was 20 years ago, you are either independent or you aren't….they are not kicking me off yet."

Noble Grossart's success was built on the now largely vanished rollcall of Scottish independents on the stock market. "We acted for a whole raft of Scottish listed companies," Mr Brown says. "Now once you get past the two bus companies, a couple of engineering and a few financial services companies, that's it. That has an impact on other things I am involved in, for example, the Edinburgh International Festival - in 2006 we had £400,000 of sponsorship from our four biggest commercial sponsors - they now give us nil."

But he goes on: "Sponsorship of the arts has continued. Small and medium-sized companies are still prospering. I think Scotland has been fairly resilient in maintaining employment and our (SFE) members still have 100,000 people employed in the sector, the same as in 2008."

The veteran financier is unshaken in his prescription for cleaning up the industry. "Regulation doesn't work. It comes back to good behaviour…..you have to have regulation and it was said to be light touch, but in a whole number of areas it was no touch - they were very concerned with some areas, the slightly easy ones, but didn't have the rigour or the quality of people at the time to deal with it."

He concludes: "Maybe this is idealistic, maybe good behaviour is a very difficult thing to get back, but if folk aren't doing the right thing, simply splitting the FSA may not be the answer."