Former Town manager John Duncan has died, aged 73, the League Managers Association has announced.
The Scot, who died peacefully at home having recently been ill in hospital, was in charge of the Blues between June 1987 and May 1990, having been recruited from Chesterfield following Bobby Ferguson’s departure.
A forward with Dundee, Tottenham, Derby and Scunthorpe during his playing days, Duncan rejoined the Spireites three years after leaving the Blues and famously took them to the FA Cup semi-final in 1997, eventually losing to Middlesbrough in a replay.
Early in his career he had spells as manager with the Iron and Hartlepool and later worked at Loughborough University.
Current Town manager Kieran McKenna said he met Duncan on a number of occasions.
"It’s sad to hear. John was a fantastic man,” he told the club site. "I managed to meet him quite a few times.
"I came across him in my time at Loughborough University. He had a great career and was a great person. Of course, my thoughts go to his family.”
Sir Alex Ferguson CBE was among the first to pay tribute: "I will always remember John with a great deal of respect and affection.
"When I was playing and managing in Scotland, I remember him playing up front for Dundee and then of course he went on to be an exceptional striker for Tottenham.
"I’ll never forget John, as manager of Chesterfield, leading his second division team to the 1997 FA Cup semi-finals which really was a fantastic achievement.
"In his role as LMA technical manager, I know first-hand what an invaluable asset he was to the association, working tirelessly and sharing his superb knowledge of the game. John understood the needs of his fellow LMA members and the importance of a collective voice.
"John had such humility and a great sense of humour and I spoke with him only a matter of weeks ago. I will miss seeing him and I send my deepest condolences to his daughters, his sister, his partner and their families.”
Sean Dyche, a friend and former player, added: "I worked with John for a number of years whilst at Chesterfield through some of the best years in the club’s history.
"He was an excellent manager who always worked to get the best out of all of his staff and players in order to mould a team into one that could challenge and be successful.
"He was not only a manager to me, as he became a friend and a mentor as my career progressed from player to coach and onto being a manager. I always appreciated his knowledge and help and I reached out to him many, many times for an opinion and support whenever I felt necessary.
"His dry wit and sense of humour were always intact if and when he felt it was the right moment. My respect for him runs deep and I was so fortunate to get the chance to tell him so recently.
"My heart and thoughts are with his family, especially his three brave daughters who have helped him so much over the last months.
"A loss to football and a big loss to me personally, but he won’t be forgotten by me or by all those who played under him or knew him”.
LMA chairman Howard Wilkinson said: "In the 42 years I have known John, his modesty has shone through. Never have I heard him mention his phenomenal goalscoring record as a professional player - a goal every two games.
"When I was at Sheffield Wednesday, he was at Chesterfield, so our paths crossed frequently, enjoyably and always fruitfully. You could play against John’s team and, at the end of the game - win, lose or draw - John would still be John.
"We were fortunate to have him as a loyal, honest, experienced, knowledgeable and hardworking member of the LMA team. He was never afraid to speak his mind but, when he did, it was only and always in the best interests of our members and the game he loved. His passing will leave a huge hole.
"I know I speak for the whole LMA team and his friends when I say we will remember John and miss him dearly. John’s family and many friends are in my thoughts.”
LMA chief executive Richard Bevan OBE added: "Everyone at the LMA is utterly devastated by John’s loss. For so many years, John has been an integral part of the team.
"His total, lifelong dedication to football meant he brought unrivalled knowledge to his role. Always strong-minded, John was a passionate advocate for quality improvement across all aspects of the professional game, working alongside football’s stakeholders for the good of everyone involved. He represented the views of his fellow members with passion and humility.
"John was a caring member of the team and we will never forget his gentle sense of humour. We send our sincerest condolences to John’s daughters Louise, Marie and Evette, his sister Avril, his partner Carol, his grandchildren and all of his family and friends at this very sad time.”