Mr Graham, 64, joined Thornton, Dickie and Brand as they then were in 1984 and was appointed partner four years later at the age of 27 to Thornton Oliver.

He served eight years as chair, starting in 2016, and has seen Thorntons grow to become one of the country’s largest legal practices.

To support the firm in the run-up to his retirement as a partner, he took up a role as senior partner at Thorntons, a key leadership position driving forward a number of projects for the firm, whilst retaining his ambassadorial role representing Thorntons and its people across Scotland and beyond. He will now act as a consultant to the business.

He said: “It has been the privilege of my professional life to have helped my colleagues to realise our common goal of seeing Thorntons expand from its traditional North East market to becoming a truly nationwide firm, with 15 offices throughout Scotland, including Edinburgh, Glasgow, Inverness and Perth.”

Mr Graham, who is one of the best-known business figures in Tayside, specialised in conveyancing law and is recognised as one of the country’s leading experts in the field, presenting for the Law Society of Scotland and other organisations on complex cases, and helping inform changes in the law.

He said: “I am enormously grateful for the many messages of support I have received from partners, colleagues, clients and friends. I have always sought to ensure that Thorntons focused on doing the right thing for our people, for our clients and for our communities.

“I am proud that, as we have undergone significant growth, particularly over the past five years, we have preserved the direct, personal client approach for which the firm has been known for decades and looked after our colleagues. That culture is what sets us apart.”

The firm’s managing partner Lesley Larg said: “Colin is rightly regarded as being ‘Mr Thorntons’ and has played a vital role in leading the firm with a rare combination of business insight, integrity and compassion for our people.

“He is enormously well-respected for his tremendous leadership and for his insistence on adherence to the highest professional and personal standards at all times. It is no coincidence that his eight years as chair saw the longest and most sustained period of growth in the firm’s history.

“The impact he has made on our business will never be repeated, and I know I speak for many, many members of the Thorntons team when I say that he has been a uniquely positive influence on my own career. We are all looking forward to his ongoing, valuable contribution in his important new role.”

As well as his decades-long leadership position within Thorntons, Mr Graham has played a leading role in many other organisations over the years, including as chair of RSPCC Dundee, treasurer of the Ninewells Cancer Research Appeal, captain of Dundee High School FP Rugby Club and as chair of NHS Tayside Primary Care Disciplinary Panel.