Brankin announces plan to quit parliament next year

The former minister said she wanted to spend more time with her family and take up other roles in public life.

Ms Brankin, 60, who has been the MSP for Midlothian since the start of the Scottish Parliament in 1999, had already been formally selected to stand again.

One senior party source said: "This has come out of the blue. The reselection process took place just two or three months ago and there had been no indication she was thinking of standing down."

Her decision will spark an internal contest to find a new candidate for what should be a safe Labour seat. Boundary changes due to come into effect next year mean Midlothian is split into two seats, with the biggest part of the county, including Dalkeith, linked with Musselburgh while the southern part, including Penicuik, linked with parts of the Borders.

Among those now tipped to battle it out for the Midlothian North & Musselburgh nomination are Midlothian provost Adam Montgomery; Simon MacFadyen, Ms Brankin's researcher for the past 12 years; Midlothian council leader Derek Milligan; and former deputy council leader Jim Muirhead.

Former Edinburgh Lord Provost Lesley Hinds came close to being selected for Midlothian in 1999, but today she ruled herself out of going for the seat because she has just been chosen to fight Edinburgh West.

Ms Brankin said it had been a "privilege and an honour" to represent her constituents.

She said: "After 30 years of being active in the Labour Party I feel the time has come to step aside. I intend to pursue other roles in public life and spend more time with my family. I shall continue to support the Labour Party."

Ms Brankin, who served as chair of the Scottish Labour Party before devolution, was diagnosed with breast cancer 10 years ago. But she returned to work as deputy environment minister in the then Labour/Lib Dem executive just weeks after surgery.

In 2001, her effigy was burnt by angry fishermen in a row over decommissioning.

She also served as junior culture and sport minister and communities minister.

She stood down as Labour's education spokeswoman at Holyrood earlier this year, saying she needed more time to look after her elderly mother.

But she recently took over as convenor of Holyrood's public petitions committee when Frank McAveety stepped down after making inappropriate comments about an audience member.

Scottish Labour leader Iain Gray said Ms Brankin's departure would be a "big loss" to the party.

He said: "She has served with distinction as MSP for Midlothian and as minister in the first two terms of the Scottish Parliament."

"She has served with distinction as MSP for Midlothian and as minister " .