The Scottish Conservative leader, Ruth Davidson, has ruled out ever taking the UK leadership for the sake of her mental health and relationship.

Davidson, who is pregnant with her first child, told how she had self-harmed and had suicidal thoughts when she was younger.

She has been frequently tipped as a future leader of the UK party due to her popularity and electoral success.

But she explicitly ruled out such a move and dismissed claims she could take a peerage or move to England and become an MP as “bollocks”.

Asked if she would ever run, Davidson told the Sunday Times: “No. I value my relationship and my mental health too much for it. I will not be a candidate.

“On a human level, the idea that I would have a child in Edinburgh and then immediately go down to London four days a week and leave it up here is offensive, actually offensive to me.”

In extracts from Davidson’s memoirs, printed by the newspaper, she said the suicide of a boy from her home village when she was 17 sent her into a “tailspin”.

A year later, she was diagnosed with clinical depression, but the medication gave her “desperate, dark, terrible dreams”.

“I started having suicidal thoughts,” she wrote.

Davidson said she was still frightened of going back to the “psychological place I once inhabited”.

She said she turned to “structure, exercise, forward momentum, measurable outcomes” when she felt anxious.