John Bute spent much of his time on his namesake Scottish island, at his ancestral home, Mount Stuart, and had chaired the Board of Mount Stuart Trust since 2005.
Full name John Crichton-Stuart, the 7th marquess, was a former Formula 1 driver who raced under the name Johnny Dumfries and won the 24-hour race, Le Mans, in 1988.
His family issued a statement describing him as a “devoted husband, father, brother, uncle, son and grandfather and loved by all”.
It also said: “The indomitable spirit and energy which Johnny brought to his life will be greatly missed, and the immense warmth and love with which he embraced his family.
“His heart was firmly rooted on the Island of Bute where he spent much of his time. Johnny chaired the Board of Mount Stuart Trust from its active inauguration in 2005 when Mount Stuart and its gardens opened to the public, and its rural estate was vested into the charitable trust.
“He was a moderniser and an inspirational thinker, transitioning a family home to a progressive, working visitor facility and estate.
“His island projects include the internationally respected Bute Fabrics and, most recently, the Kerrylamont Centre for Rural Excellence and Bute Yard. He was a philanthropist through his foundation, particularly focusing on Scotland and the West Coast.
“His family request privacy at this time.”