David Cairns’s resignation as Minister of State at the Scotland Office will not resonate much south of the Border other than to confirm a continuation of the internal party turbulence hitting Gordon Brown and Labour.

However, in Scotland, the softly-spoken ex-priest had a more high-profile role as a chief defender of the Union in the Scottish media against the Nationalists’ push for independence.

Mr Cairns, 42, who has close political links with Siobhan McDonagh, who was sacked last week as a junior whip for calling for a leadership challenge to Mr Brown, could also not be numbered among the Prime Minister’s biggest fans. He is also close to John Reid, the former Blairite Home Secretary and also a Scottish MP.

Mr Cairns’s disillusion with Mr Brown reached a peak over the last few days, according to close colleagues who said he complaining bitterly about the lack of direction of the Brown Government as well as what he considered the simple policy mistakes made by the Prime Minister.

However he appears to have thought hard before jumping and had to endure entreaties from some of his party colleagues to carry on.

His last big role for Mr Brown was to help manage the campaign in the Glasgow East by-election which Labour lost spectacularly to the SNP. It is believed that he felt that his ministerial days were numbered in any case because Mr Brown is unlikely to retain a number two in the Scotland Office when he undertakes his reshuffle in a few weeks time.

Mr Cairns became Labour MP for the then constituency of Greenock and Inverclyde in 2001. Born in Greenock, a town at the heart of what was then the thriving shipbuilding industry of the lower Clyde, he became a Roman Catholic priest and from 1991 to 1994 served in Scotland and then south London.

From 1994 to 1997 he worked as a director of the Christian Socialist Movement and secretary for Labour’s socialist societies.

While working as a parliamentary researcher for Ms McDonagh, he served as a councillor in the London borough of Merton and was later selected as a prospective Labour candidate for his home town.

However he discovered he was barred from becoming an MP because of the House of Commons (Clergy Disqualification) Act 1801 and the Catholic Relief Act 1829 which prevented former Roman Catholic priests from being elected to Parliament.

Ms McDonagh introduced the House of Commons Disqualification (Amendment) Bill in Parliament in June 1999, but the Bill fell. The Government subsequently introduced the House of Commons (Removal of Clergy Disqualification) Bill to remove these restrictions and it was passed in May 2001, thus ensuring that Mr Cairns could be elected in what was a rock-solid Labour seat.

He took on his junior ministerial role at the Scotland Office in 2005, becoming a minister of state two years later.

While never someone given to using colourful language, he hit the headlines in Scotland last year when he referred to those politicians and non-politicians pursuing more powers for the devolved Parliament in Edinburgh as “the McChattering Classes.”.

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