Mr Donaldson is retiring at the end of July and will be succeeded by his son and deputy chairman, Michael Donaldson, who will co-lead and co-manage the business with his brother, Andrew Donaldson, who took over as CEO in April.

He will be handing over the reins of the company, which has been operating in Fife for 160 years, to a sixth generation of the family.

Mr Donaldson joined the firm in 1975 after graduating from Heriot-Watt University with an MSc in Business Studies. He grew up spending his school holidays working for the family business, but his first official role was as a sawmiller, before moving into sales in the late 1970s. He took over from his father as managing director in 1985.

During his tenure, he has overseen the expansion of Donaldson’s from a small business in Fife, Scotland, to a national company with seven subsidiaries, operating from 31 sites across the UK with over 1,000 employees and a turnover of around £225 million.

Developments and strategic acquisitions in that time include the creation of Donaldson Timber Engineering (DTE), which now has nine branches; timber merchant MGM Timber, which has 14 branches; expanding James Donaldson Timber and moving into MDF with the purchase of Palgrave Brown; insulation product manufacturer, Nu Style; Cambridge Roof Truss; and most recently, doorset and bespoke joinery specialist, Rowan Manufacturing and kitchen manufacturer, Smith & Frater.

Mr Donaldson has credited much of his confidence in growing the business to the time he spent at Harvard Business School in 1994.

In 1988, he became the first Scottish chairman of the Timber Research and Development Association (TRADA). He was also president of the Scottish Timber Trade Association (STTA) from 2004-6 and was president of the Timber Trade Federation (TTF) from 2006-8.

Commenting on his retirement, Mr Donaldson said: “I have been extremely fortunate to have spent my career working with something I love, making a product that I love, in a business where I have been able to develop it into what I think it should be.

“I always wanted to work for the family business – I have wood in my DNA – and I think I can say that I’ve made the most of my time here! I always said that I hoped to retire at 65, in our 160th year of business, and the time is definitely right to pass the business on to the next generation.

“I’m incredibly proud of what we’ve done with the business over the last 45 years – and indeed over the last 160 - and I’m happy to be going out on a high. To have both Mike and Andy taking over is the ideal scenario and I’m excited to see where they take it next. Meanwhile, I’ll be golfing, fishing and spending more time with my wife, Val, who has been an incredible support to me throughout my career.”

Along with his roles in the timber industry, Mr Donaldson is former chairman of Scotland’s spa hotel resort, Crieff Hydro; a former chairman of Securities Trust Scotland; and the current chairman of Baillie Gifford’s Shin Nippon in Japan.