One-time Scottish international decathlete Ben Thomson has, at the tender age of 43, moved into semi-retirement for now by handing over the reins of Edinburgh-based investment bank Noble Group to former Merrill Lynch executive Angus Macpherson.

Thomson becomes the Scottish investment bank's part-time chairman, following the retirement of Tim Noble, who co-founded the group as Noble & Company alongside his brother Sir Iain Noble in 1980. The reshuffle was signalled back in November but this is the first week of the new arrangements.

In spite of his youth, Thomson is signalling no appetite for another full-time role meantime but plans instead to assemble a portfolio of non-executive directorships as well as attempting to fuel debate about contentious political issues with a bearing on the Scottish business scene.

Asked what he would do now, Thomson replied: "All sorts of mischief."

Prefacing his remarks by claiming he is "not party political", Thomson said: "I will continue to participate in the debate on fiscal autonomy for Scotland.

"Instead of seeing that as a scare story, I will be trying to persuade others in financial services and the business community to recognise it as something that could throw up some fantastic opportunities for Scotland."

His support for fiscal autonomy comes at an interesting time, with the independence debate in full flow ahead of the Scottish Parliament elections in May.

Thomson's latest comments follow support for Scottish National Party leader Alex Salmond from Sir George Mathewson, former chairman of Royal Bank of Scotland. Salmond worked previously as an economist for Royal Bank.

Thomson comes from a family of great achievers. His two grandfathers and two of his great-grandfathers won Nobel prizes for physics.

He has transformed Noble Group in his 10 years as chief executive.

With offices in Edinburgh and London, Noble Group provides a comprehensive investment banking service through its Noble & Company subsidiary.

This has carved itself a niche in advising companies on their Aim listings and acts as adviser, sponsor and broker to more than 40 companies with market capitalisations in the £2m to £250m range.

Noble spun off its equity fund management arm, now called Cornelian, in 2000, but retains a fund management business that specialises in managing a range of alternative asset classes including PFI funds and private equity.

Macpherson, 37, who joined the group in January, was previously head of capital markets and financing for Merrill Lynch's Asian operations.

"He's an extremely talented guy who wanted to live in Scotland," says Thomson.

Adam Grant, who joined Noble Group last October, has taken over as group finance director. He was formerly European finance director at Morgan Stanley.

Completing the reshuffle, Angus Macdonald, owner of Financial News and founder of Edinburgh Financial Publishing, is stepping down as a non-executive director of Noble Group. The changes all took effect at the group's annual meeting last Friday. John Llewellyn-Lloyd and Henry Chaplin, who respectively head Noble Group's banking and fund management arms, remain on the board as directors.

Thomson said he will remain as a director of both Scottish Financial Enterprise and the Scottish Executive's financial services advisory board. Already a non-executive director of the Martin Currie Portfolio investment trust, he said he will be seeking additional non-executive roles.

Thomson said: "I'm delighted that Angus Macpherson and Adam Grant are joining the board as chief executive and finance director. Their backgrounds at Merrill Lynch and Morgan Stanley will bring the necessary experience to drive the company to the next stage."