Labour's top official in Scotland announced yesterday she is to stand down after 27 years working for the party.

Lesley Quinn joined as a junior shorthand typist aged 16 and rose to become general secretary of the Scottish party eight years ago.

She is to "seek new challenges," according to a statement from Labour's headquarters at John Smith House. There has been speculation in the past that she would be a strong contender to secure a parliamentary candidacy, having proven herself a tough and respected operator.

Ms Quinn will stand down in five months time, after the Scottish Labour conference in Aviemore next March. Her departure follows a Holyrood election result last May that toppled Labour from its 50-year dominance of Scottish politics.

The general secretary has taken some of the criticism of Labour's campaign, voiced privately, but leading backbench MP Ian Davidson said: "It would be a mistake if she was made a scapegoat for the party's failures in the recent election because clearly our difficulties went beyond any individual."

There were tributes to Ms Quinn from Prime Minister Gordon Brown, his predecessor Tony Blair, Scottish Secretary Des Browne and Scottish Labour leader Wendy Alexander.

The next general secretary, a post previously held by former First Minister Jack McConnell and former Scotland Secretary Helen Liddell, will be appointed by a joint panel of the party's Scottish and UK executive committees.

Ms Quinn, aged 43, said: "I have spent 27 years working for the Labour Party spanning five leaders, two Prime Ministers, three First Ministers and have stories to tell about them all. I have more than exceeded all of my personal goals and ambitions in a demanding role.

"There were times when we had to keep the faith that one day there would be a Labour government, and now, 10 years into a Labour government, I feel a tremendous sense of achievement."

She went on: "I feel now is the time for me to build on achievements within the Labour Party, having now accomplished all of my goals, and take some time to set out the next chapter in my future. I have a number of options."

Gordon Brown said: "Lesley has made a massive contribution to the Labour Party, and has been on an incredible journey from junior shorthand typist to general secretary. After 27 years, her leadership, counsel and experience will be sorely missed."

Tony Blair commented: "Lesley's experience, wisdom and knowledge of Scottish politics is second to none. Her advice and counsel over the years was always much valued and clearly delivered."

Ms Alexander said she was "disappointed" that Ms Quinn was going, as her wealth of experience, knowledge and leadership in the party were massive.