Former SNP leader Billy Wolfe has died aged 86 after a long illness.
He was National Convenor - party leader - from 1969 - 1979, a period that saw the party enjoy considerable election success, with 11 MPs returned to Westminster in the 1974 General Election.
Paying tribute, SNP leader First Minister Alex Salmond said: "I am deeply saddened at Billy's passing, and my thoughts are with Kate and his children David, Sheila, Ilene and Patrick.
"Billy Wolfe blazed the trail in the professionalisation and organisation of the SNP - and he more than anyone transformed it into a modern political party. Indeed, the West Lothian by-election in 1962 was the moment when the SNP broke through as a central and driving force in the Scottish political process - and the party went on to achieve outstanding success in the mid-1970s under his leadership.
"Billy was also incredibly influential in developing a social democratic ethos for the SNP in terms of its political identity - something which there were doubts about when he was leader, but which came to fruition in later years, and was vital in the success we enjoy today.
"Billy was committed to public life and the causes he believed in - working with others, for example, in the campaign for nuclear disarmament - and he will be greatly missed both within and outwith the ranks of the Scottish National Party.
Born in 1924, he joined the SNP in 1959 and stood for election in the 1962 by-election against Tam Dalyell. He came second, with a swing of 23%, in a seat where previously the SNP had little standing.
He went on to fight for the West Lothian seat at a further six General Elections.
Billy Wolfe brought an awareness of the need for professionalism in the organisation of the party, and helped establish the SNP as a left of centre political party.
His 1962 campaign slogan "Put Scotland First" went on to become an extremely popular campaign slogan used throughout the 1960s and 1970s.
He stood down as party leader following the 1979 General Election, and was succeeded by Gordon Wilson.
From 1991 to 2008 he served variously as a member of the SNP National Executive Committee and an elected member of National Council.
