THE Presiding Officer of the Scottish Parliament, Tricia Marwick, is to step down from Holyrood after admitting she is "not invincible" following a cancer scare.

The Fife MSP, pictured above with Nicola Sturgeon and Ruth Davidson at an event to launch a music competition, revealed she would not contest next year's Holyrood election.

Ms Marwick, 61, has fought back to health after being diagnosed with bowel cancel two years ago but said she wanted to spend more time with her family.

She said: "When I was diagnosed with bowel cancer in 2013 it made me realise I wasn't invincible.

"The sad loss this session of four MSPs from the 1999 intake has affected me deeply.

"My health is good and all my tests show that I remain clear of cancer. However, my family have had to make many sacrifices over the years and I want to ensure that I can spend more time with them, particularly my two grandchildren."

Ms Marwick was first elected in 1999 as regional MSP for Mid Scotland and Fife.

She took the former Central Fife constituency in 2007 and the redrawn seat of Mid Fife and Glenrothes in 2011.

Elected Presiding Officer the same year, when she left the SNP to take on the politically neutral role, she has pursued a reforming agenda at Holyrood, reorganising the parliamentary timetable to ensure ministers can be questioned on issues in the news.

She is also championing efforts to reform the parliament's committee system, following complaints the SNP dominated committees are failing to hold ministers to account.

Among the changes being considered, she has called for committee conveners to be directly elected in a bid to have more independent-minded MSPs installed in key jobs.

Ms Marwick was made a Privy Councillor in 2012, giving her the title 'Rt Hon'.

Looking back on her time in parliament, the former charity official said: "I have been active in politics since the mid-80s and for some of that time held down a full-time job, looked after my children as well as campaigning.

"I have been an MSP since 1999 and I am convinced this is the right time for me to leave the Parliament and frontline politics."

She said he would not retire completely and hoped to maintain a role in public life.

Born in Cowdenbeath and raised in Fife, she said it was the "greatest privilege" to represent her local area as she thanked her constituents.

She said she was proud of the parliamentary reforms she has made, but, in a message to fellow MSPs, stressed: "More needs to be done but I am pleased to have started the debate around elected conveners and what I believe to be essential committee and wider parliamentary reform.

"I will continue to put my energies into the Parliament and my constituency until I step down next year."