SIR George Reid, one of Scotland’s most respected politicians, will return to the front line for the first time in a decade today to rally opposition to Brexit.

The former Presiding Officer at Holyrood said he felt a “moral responsibility” to speak out against a change which would “negate everything I’ve believed in all my public life”.

Sir George, 77, who switched to academia after leaving parliament in 2007 and underwent successful surgery for bladder cancer in 2013, will address a meeting of the European Movement in Edinburgh tonight.

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First elected an SNP MP in 1974 after standing as a “European social democrat”, he told the Herald he was too old for a leading public role, but could not ignore the risks posed by Brexit, adding: “You can either whimper and whine or fight back. If you don’t fight back you’ve lost already.”

He said Brexit reminded him of Donald Dewar’s famous words at the opening of the Scottish Parliament in 1999: “This is about who we are, how we carry ourselves.”

He said: “Brexit is as big as Suez in dictating the next 50 years. We’re stripped of the identity we’ve had for 40 years, and in terms of carrying ourselves, it’s carrying ourselves in a world characterised by a race to the bottom, low wages rates, and threats to social cohesion.

“It’s about the sheer threat to what sort of country we are and how we conduct our affairs.”

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He said that, despite the differences between Holyrood parties, there seemed to be a “Scottish bottom line”, which was to maintain the fullest possible links to Europe, and that consensus should be used to extract a better deal for Scotland from Theresa May.

He wanted to “to get as close as possible to a Scottish common voice, to see that in opinion polls, and to make that very clear to a Cabinet that I don’t think gets Scotland.

“It is to make clear it’s not just the SNP [opposed]. It’s bigger than the SNP and nationalism. This is about a nation, where it’s going, how it perceives itself, and what sort of society it will be. The more than comes through, the more they will think about that.

“There has to be as much cross party openness and engagement as possible, and a programme of engagement in Europe itself, including bringing speakers from Europe here.”

He said Brexit might not happen if public opinion swung against it, but it was impossible to predict the twists and turns of the next 18 months of negotiations. “I don’t rule it out,” he said.

A member of Nicola Sturgeon’s Standing Council on Europe, Sir George said the First Minister had been “up for compromise and pragmatic settlements all the way through”, but her plan for a bespoke Scottish Brexit had met silence from the UK government.

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With Ms Sturgeon warning of a second referendum if her plan to stay in the EU single market is rejected, he said: “If we’re not over the Rubicon, we’re getting close to it.”

Sir George was an MSP from 1999 to 2007, and the neutral Presiding Officer for four years.

He then filled more politically neutral roles as Lord High Commission to the Kirk General Assembly, Lord Lieutenant of Clackmannanshire and Electoral Commissioner, so has not rejoined the SNP, but remains close to its leadership and supportive of its aims.