A third SNP MP has announced a decision to stand down ahead of the general election expected before the end of next year.

Angela Crawley revealed in an open letter posted on social media this afternoon that she would not be putting herself forward as a candidate at the poll.

The MP for Lanark and Hamilton East said being a Westminster parliamentarian had involved "many difficult compromises" and it was now time to put her partner and their young family "at the centre of my daily life".

She wrote on Twitter: "I have been privileged to stand as the MP for Lanark and Hamilton East since 2015, with unwavering support from family, friends and SNP branches. My open letter explains why I am not standing at the next General Election."

In her letter Ms Crawley said: "Serving my community has always been my number one priority.

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"This has, however, come at a difficult personal cost and required many difficult compromises.

"The unpredictability of Westminster can be challenging with a young family. It is now time to put my partner and our young family at the centre of my daily life.

The Herald:

SNP MP Angela Crawley, pictured in 2015, has said she will not be putting herself forward as a candidate at the next general election. Photo Nick Ponty, The Herald.

"They deserve my full love, attention and dedication. With them in mind, I have made my decision not to offer myself as a candidate at the next general election."

Ms Crawley's decision to stand down at the general election follows that of the SNP's former Westminster leader Ian Blackford and that of the party's Westminster treasurer Peter Grant.

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Ms Crawley is currently the SNP’s attorney general spokeswoman and has previously held roles as SNP spokeswoman for defence procurement and equalities, and has served on the justice, health and social care, and women and equalities select committees.

Her campaigns have included those for paid miscarriage leave, access to benefits for sick and disabled peoplem and for reform of the child maintenance service.

In her letter she said she would be proud of her and her team's successes in the help they had provided to "innumerable constituents" and that she would continue to campaign for independence.

"Having been an SNP member since my student days – and after more than 15 years as an elected politician – I recognise not just the huge potential of our part of the world, but the work needed to bring it to fruition.

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"I will continue to campaign tirelessly for independence and a brighter, better future for my family, my community, and the people of Scotland.

She added: "I look forward to supporting the First Minister and the SNP in sharing that vision and to a future Scottish independence referendum. I will continue to serve my constituents to the best of my ability until the next General Election, and my office will remain open and accessible until that time."

Ms Crawley's decision not to fight the next election will leave the SNP searching for a third new MP hopeful.

A shock poll for the party last weekend put Scottish Labour on course to beat the SNP at the general election with Anas Sarwar's party on course to win 26 seats and the SNP 21.