As the most recognisable and most often quoted member of the UCS shop stewards he became the public face of the work-in, which attracted both national and international attention.

UCS was millions of pounds in debt and thousands of jobs, both directly in the yards and indirectly among suppliers, were in jeopardy.

After a protest campaign lasting more than a year the Government was forced into providing a £35 million lifeline for the shipyards.

At the time of the work-in Mr Reid was a member of the Communist Party, but later switched allegiance and joined Labour.

In 1978 he was controversially selected as the Labour candidate for Dundee East after having been a member of the party for only a few months.

He stood against Gordon Wilson in the 1979 General Election and came within 2500 votes of unseating the SNP leader.

So it is ironic it should be in Dundee that, sitting alongside Mr Wilson’s successor Alex Salmond, he has now announced his conversion to the SNP.

“To me, New Labour has abandoned and betrayed all the principles that were fundamental to the Labour movement in Scotland,” Mr Reid said.

“I have waited a long time to see forces emerging within theew Labour party that would bring the party back to its roots.

“But I have been waiting in vain and, with every year that passes, Tony Blair and New Labour move further to the right. They are now indistinguishable from the Thatcherite Tories.”

Mr Reid said the SNP was a social democratic party which adhered to the values the Labour movement was based on.

Mr Salmond welcomed Mr Reid to the SNP.

“He is not only one of Scotland’s most respected trade unionists, he has also shown himself over many years to be a man true to his principles and those of the labour movement,” he said.

Mr Reid said he came from that element in the Labour Party which had always been in favour of home rule for Scotland.

Asked if that meant full independence rather than the devolved Scottish Parliament, he said he was in favour of a referendum that gave the Scottish people the right to decide whether they wanted independence.

“I would argue for a Yes vote in that referendum,” he said.

Mr Reid stressed that was not an anti-English attitude and said he disliked such attitudes being expressed by Scots.

Asked if he would be standing as an SNP candidate in the next Holyrood elections he appeared to dismiss the idea by saying he would be 75 by then.

However, Mr Salmond chipped in, “Sometimes people who say they are not going to stand for things change their mind.”

That was an obvious reference to his own protestations that he would not be a candidate for the leadership of the SNP after John Swinney stood down.e waited a long time to see forces emerging within the New Labour party that would bring the party back to its roots.”