Town vice-president Harold Smith has died aged 89. Smith had been a fan of the club since 1924 and was a director for more than 30 years.
Chairman David Sheepshanks paid tribute: "He was the last surviving member of the 'infamous' Cobbold era.
"He served diligently as a director with immense pride and dignity from 1964 to 1995 when he voluntarily stood down and was made vice-president for life.
"A man of integrity and honour, Harold was an avid supporter of this club since the 1920s and rarely missed a match - regularly attending reserve team and youth games until his death.
"As a young director joining the board in 1987, I remember Harold as a most distinguished member of the Football Association, where he represented the Suffolk FA and served on the National Disciplinary Committee.
"Harold will be sorely missed. One of my most heart-warming memories I have of him was seeing him enjoying reminiscing with Sir Bobby Robson over lunch before last weekend's game against Crystal Palace.
"Our deepest sympathies and condolences are with his family and friends at this sad time."
Flags are flaying at half mast at Portman Road and there will be a minute's silence at the Hull City home game a week on Saturday, when the players will wear black armbands.