LEADING centre-right historian Michael Fry claims Scottish Tories “seldom have anything to say except on the constitution”.

Fry, a former Tory candidate, believes Ruth Davidson’s party is gripped by a hardline Unionism that seeks to appeal to a hardcore of just 20 per cent of Scots. He said the party had increasingly collapsed into an “unyielding, almost fanatical Unionism”.

Fry, the author of eight books of Scottish history, said that drift started during the Thatcher era and has continued under subsequent leaders, including Davidson.

He suggested the Scottish Tories now deliberately avoided having specific policies other than on the constitution in order not to alienate those who are want to vote for a Unionist party, above all else.

Fry said: "It's certainly true that the Scottish Conservative Party seldom has anything to say except on the constitution. Once you start to have policies you start to turn people off.

"It's an obvious strategy to appeal to 20 per cent of the electorate."

Fry maintains the Scottish Tories under Davidson are now more hardline on the Union question than in the 1950s and 1960s when the party in Scotland had the title of the Unionist Party, before becoming an official part of the Conservatives in 1965.

He said: "The old Unionist party had a much wider spectrum and Govan used to elect Unionist MPs. It was part of this old working-class Unionism.

"It was largely based on Scottish steelworkers and those in the shipyards – skilled workers – who regarded the Tory order as a way to defend their privileges.

"There was a much wider variety of interest in devolution in the party. Under Macmillan, for example, there were various reforms to strengthen the Scottish Office."

Fry said in the 1980s the Scottish Tories hardened their Unionist stance when Margaret Thatcher was Prime Minister and figures such as former Scottish Secretary Michael Forsyth came to prominence.

He suggested this attitude was reflected in the uncompromising Unionism promoted by Davidson.

Adding: "The kind of hardline Unionism in Scotland did not really come about until the years of Thatcherism and Michael Forsyth.

"That unyielding, almost fanatical Unionism came to the fore."