David Cameron's Government suffered a serious blow as one of its most experienced Cabinet members resigned.

The Glasgow-born leader of the Lords, Lord Strathclyde, stood down saying that he wanted to return to a career in the private sector.

It brought to an end a Conservative frontbench career that had lasted 25 years and spanned the premierships of three Tory Prime Ministers.

In recent years Lord Strathclyde has steered the Lords through a series of stormy patches as Labour and rebel peers lined up to defeat the Coalition Government on issue after issue.

But a number of tough battles still lie ahead for his successor – not least over the upcoming gay marriage proposals.

Lord Strathclyde told the Prime Minister of his decision to leave Government after Christmas.

But the news of his resignation only emerged yesterday, and initially threatened to overshadow the Coalition's much-heralded relaunch, breaking just hours before David Cameron and Nick Clegg's press conference.

Almost immediately Downing Street announced that he would be replaced by a politician famous for attempting and failing to resign during the last reshuffle.

Lord Hill of Oareford, a former education minister, allegedly tried to leave Government back in September. He is reported to have kept his job only because the Prime Minister was so distracted that he did not hear his resignation request.

Mr Cameron dismissed that story yesterday, saying that it "wasn't quite right".

Lord Strathclyde has been a member of the House of Lords since 1986 and was first appointed to Government two years later when Margaret Thatcher made him a trade and industry spokesman.

He remained on the Conservative front benches for more than two decades, serving as a whip and a minister in the departments for Scotland, employment, environment and trade and industry in the Thatcher and Major administrations. He was one of the hereditary peers elected to remain in the reformed upper chamber in 1999.

He had served as opposition leader in the Lords from 1998, and was made leader of the House in 2010 when the Coalition came to power. In a nod to the difficulties that lie ahead for his successor, he said that he felt that the upper House now needs "a new Leader to see it through different challenges in the years ahead".

He added that when he was first appointed to Government he "never believed it was a career for life".

He said: "I do not see a political career as the cap to everything and would like, while there is still time, to take up other threads of my life and other interests."

In a letter accepting his resignation, Mr Cameron praised Lord Strathclyde as "an outstanding Leader of the Lords".

Mr Cameron paid tribute to him, saying: "He has done a great job for the House of Lords, for the Conservative Party and for the Coalition Government."

"I am obviously sad to see him go because he is a brilliant public servant, knows the House of Lords inside out and has been a really valued colleague to me."