The Christian Socialist Movement said it was “saddened” by news of David Cairns’ death on Monday after a short illness.

The Labour MP and former Scotland Office minister died in hospital from acute pancreatitis, which he had been receiving treatment for since March. He was 44

The former Catholic priest leaves behind his partner Dermot and brother Billy.

“He will be much missed,” said CSM. “David was a good friend of CSM and many members will remember him with great affection.”

Mr Cairns was previously CSM’s Coordinator and is credited with making the organisation more professional and helping it to engage more effectively with policy debates in the Labour Party.

He was first elected to parliament in 2001, as Labour MP for Greenock and Inverclyde, now simply called Inverclyde, and served as parliamentary Under Secretary of State and Minister of State at the Scotland Office from 2005 until 2008.

CSM Chair Alun Michael MP said: “CSM wouldn’t be around today in its present form if it wasn’t for the work David and others did all those years ago.”

CSM Director Andy Flannagan said: “David was a lovely guy who continued to encourage CSM even while busy putting Christian values into practice as an MP and minister.”

Labour leader Ed Miliband said Mr Cairns would be “missed beyond measure”.

“David was an immensely talented Member of Parliament who campaigned diligently on behalf of his constituents in Greenock and Inverclyde,” he said.

“A highly effective Minister of State in the Scottish Office, he was Labour through and through and yet was much-respected across the political divide.

“He was also a man with a wide hinterland. As a former Catholic priest he brought a sensitive understanding of others and a ready wit to politics and he never shied away from saying what he believed to be true. The Labour Party will miss him profoundly. He was a good man."