ALEX Salmond has been underrated by London opponents because they consider him "provincial and lower middle class", according to a new history of contemporary Scotland.

He has also been dismissed as a "scruff" whose off-duty tendency to dismiss a collar and tie persists to this day.

The claims come in a new book by Herald columnist Iain Macwhirter, who says a key reason why the SNP triumphed at Holyrood polls was that the leader was consistently under-rated.

Macwhirter's history will be featured at Glasgow's Aye Write! literary festival and is also detailed in a new three-part documentary starting tonight on STV.

Macwhirter believes class is a persistent reason why Westminster politicians underestimated the SNP leader.

He writes: "One reason I think that there is so much antipathy to Salmond in the metropolitan intelligentsia is that there isn't anything very interesting about Salmond and there is a vague resentment that he has got where he has.

"He must be a devious trickster, a svengali, or live a double life. How could someone so ordinary be a great leader? The one place Alex Salmond really did shine, however, was – to their annoyance – in the debating chamber of the House of Commons.

"Salmond still says that he felt most at home in that chamber, more so even than in Holyrood. He was a natural debater, and loved the sense of being close to power."

He goes on: "Salmond is provincial and lower middle class, his parents were junior civil servants, and he had a very conventional upbringing, going to church on Sunday -

"His father, Robert, supported Labour, and his mother, Mary, was a Conservative. There is almost nothing remarkable to say about Alex Salmond's background – no Oxbridge firsts, or Glasgow University debating honours, or rugby caps.

"He didn't take drugs, attend raves, go on gap-years abroad, climb mountains or get arrested for refusing to pay his poll tax.

"He doesn't speak foreign languages or write novels in his spare time or do anything that might class as a 'hinterland' – except perhaps golf."

Macwhirter's book adds: "Salmond arouses very strong feelings, and seems to generate suspicion wherever he goes. The odd thing is that for all the colourful language, none of his critics seem to have ever actually pinned anything on Salmond.

"He has been one of the most minutely scrutinised politicians in Britain, with unionists desperate to find confirmation of his perfidy, and the national press ever at the ready with its cheque book."

The book says of the FM's cultural view: "He is interested in the arts, in a political sense at least, since like all nationalists he realises how important writers and artists are to any movement for national independence.

"Salmond can recite Burns, sometimes beyond the pain threshold."

Macwhirter speaks of interviews at Bute House, saying: "In the evening, the First Minister will emerge, typically in a polo shirt, belly hanging perilously over a pair of crushed slacks and scuffed tan shoes.

"The smart suits and ties are dispensed with as soon as he gets off grid. You realise that this is probably how he's been dressing since he was an economics and medieval history student at St Andrews University in the 1970s. Informality, in the Salmond circle, is almost a formality.

"When he worked as an oil economist after leaving university, first with the Government service and then the Royal Bank of Scotland, he was invariably described as a 'scruff' and censured for not wearing a tie."

Iain Macwhirter's Road to Referendum is published tomorrow by Cargo Books (£13.99). The first episode of his three-part documentary is on STV tonight at 8pm.