THE Scottish Secretary's adviser on the constitution has tried to distance himself from his fiery republican past, admitting some of his views on the monarchy were "a bit extreme".

Professor Adam Tomkins, who became an unpaid adviser to David Mundell last month, had previously railed against "the weirdness of the present generation of Windsors".

Tomkins, the John Millar Professor of Public Law at Glasgow University, also attacked "the degrading rituals of pomp and servility that accompany majesty", the "sheer unfairness" of an hereditary head of state, and claimed the royals had a "long history of tax avoidance".

He complained that monarchy was "fundamentally incompatible with democracy" because the Queen confers huge power on ministers allowing them to bypass parliament and escape scrutiny.

"You're either a monarchist or you're a democrat. You can't be both," he wrote.

"If you want an accountable government you have to choose to abandon the monarchy."

Tomkins laid bare his feelings in an article in May 2004, in which he listed the "many arguments against monarchy".

Five months later, he spoke at the 'Declaration of Calton Hill,' an event staged by the Scottish Socialist Party to rival the Queen's official opening of the new Holyrood building.

The Declaration began: "We the undersigned call for an independent Scottish republic".

According to a contemporary report, Tomkins "delivering a damning indictment of the monarchy" and said it was incompatible with democracy.

Tomkins also met the artist and author Alasdair Gray at the event, and they went on to co-author a book arguing for a republic called "How we should rule ourselves".

In it, the pair said they were both "of the left" but neither belonged to or endorsed to any party.

Tomkins is now an active Conservative.

Gray said he was "sorry" that Tomkins had dropped the republican cause.

"I suppose it depends on your degree of prosperity," he told the Sunday Herald.

Tomkins's past views are sharply at odds with those of his Tory boss in the Scotland Office.

In 2013, Mundell said pro-independence republicans were "out of touch... with the people of Scotland" and insisted "the Royal Family are part of the fabric of Scottish life".

Asked about his republicanism, Tomkins said his interest had been of a "dusty, antiquarian academic" kind and he "didn't know" if he ever signed the Declaration of Calton Hill.

"I quite like the pomp and ceremony these days. My republicanism has softened," he said.

Reminded of his written article, he said: "Yes, that sounds like me. That sounds a bit extreme.

"It's the kind of thing I probably would used to have said, but I wouldn't say that [now]."

"One of the reasons I don't worry as much about these things as I did 10 years ago is because many of the legal powers of the Crown have been taken into parliament.

"The Fixed Terms Parliament Act (FTPA) is a really good example. It used to be the case that the Prime Minister could decide when the next general election was...because they effectively wielded the old prerogative Crown power of dissolution.

"The FTPA rips all that up and it puts that power in the hands of backbenchers.

"In the sense of being a parliament man, who thinks parliament should make [key] decisions and not judges or members of the royal family or even ministers, I'm still fully signed up.

"But in terms of getting rid of the Queen and having a presidency, I'm probably not signed up to that anymore, because I just don't see the point. It's not a priority. It's not happening."

Former Socialist MSP Colin Fox, who spoke alongside Tomkins at the Declaration of Calton Hill, said: "He's gone from Cromwell's side to the Cavaliers. He should be ashamed of giving up on democracy in favour of the divine right of kings and hereditary privileges. Although that does make him pretty much at home in the Tory party."