MP Lisa Cameron rejects calls for a by-election

A former SNP MP who defected to the Conservatives has defended her decision not to stand down for a by-election.

Dr Lisa Cameron said many other MPs had changed parties in recent years without triggering such a vote.

In a BBC interview, she repeated her claims that she quit because of a "toxic culture" in the SNP's Westminster group.

She also said she regretted not leaving the party sooner as her experience had damaged her mental health.

Dr Cameron, who was an NHS clinical psychologist before she was elected in 2015, announced her defection last week just ahead of a selection meeting to pick the next candidate for the East Kilbride, Strathaven and Lesmahagow constituency.

She was facing a challenge for re-selection from Grant Costello, who was employed by the SNP as a digital manager.

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Dr Cameron confirmed she planned to return to NHS work, and would not stand at the next general election, but insisted there was no need for her to stand down sooner.

She said: "Lots of MPs move party and actually create their own parties and didn't have by-elections because it is not part of the process.

"I know Humza Yousaf had called for that, but my understanding is actually in the Scottish Parliament that was put forward earlier this year and the SNP did not support the premise that if you change party from your initial election then there should be a by-election or recall.

"So I don't think there should be one rule for them and a different rule for me."

She added: "And certainly in this parliament those who have switched parties are all men except for me so they are still there.

"Why should I be the one to go?"

The MP said she was prescribed anti-depressants and received counselling as a result of treatment she claims to have received during her time within the party.

Since making the announcement about her move on Thursday, she said she had received numerous "threatening messages".

The MP said she had to close her constituency office and had been forced to miss her daughter's 15th birthday amid security concerns.

On her decision to leave the SNP, she said she felt "isolated" within the SNP's Westminster group and there was a lot of "fear and intimidation".

She said that intensified after she defended the teenage victim of unwanted sexual advances from SNP MP Patrick Grady.

She said: "The only regret I have is that I stayed in the situation I was in for such a long time struggling and that I didn't perhaps heed the advice of the health professionals like my GP saying 'we can counsel you, we can give you some medication, but unless you change your situation, you're not going to feel any different'.

"And I just feel a tremendous relief now that I'm out of that situation and that I'm looking forward to engaging with so many new colleagues who have sent me messages asking me to join groups, to come for a coffee, to come to events."

On Monday senior SNP MP Alison Thewliss told Radio Scotland's Drivetime programme that she did not recognise Dr Cameron's claims that there were "toxic" and "bullying" elements in the SNP.

Alison Thewliss questioned Lisa Cameron's reasons for defecting to the Tories

Instead the SNP's home affairs spokesperson at Westminster accused Dr Cameron of acting inappropriately towards others in the SNP.

Ms Thewlis said: "I have heard very vociferously from members of her own branch in East Kilbride who they themselves felt as though she had taken a very bullying attitude to members of the SNP, and they quite frankly are glad to see the back of her."

She added that members in East Kilbride had been "very concerned" by the MP's behaviour "for many years" and that "slipping out the door and joining the Tories was not a huge surprise to any of them".

Dr Cameron denied the accusations, adding: "I've been an MP in the SNP for about eight years now and I've never had any word from a conduct committee regarding any bullying allegations.

"Mud-flinging is another thing and I think that that sort of thing just incites people towards a negative approach to me, particularly when I've never had any conduct complaints in the past.

"I find it very disappointing that people would say that."