Moment ex-SNP MP Lisa Cameron is cheered by Tories as she crosses the floor in the Commons to sit next to Theresa May on Conservative benches following her defection from the nationalists

Ex-SNP MP Lisa Cameron was cheered by Tory MPs today as she crossed the floor of the House of Commons to sit on the Conservative benches.

The East Kilbride, Strathaven and Lesmahagow marked her dramatic defection from the SNP by seating herself opposite her former party colleagues.

Dr Cameron sat next to ex-prime minister Theresa May and Scottish Tory leader Douglas Ross as she joined the Tory side of the Commons chamber.

Her arrival was enthusiastically greeted by Conservative backbenchers, which earned them a rebuke from Speaker Sir Lindsay Hoyle.

‘People should wait – just because you want to cheer somebody coming in, do it at the right time. Totally inappropriate,’ Sir Lindsay said, as he fumed at the interruption to proceedings.

Ex-SNP MP Lisa Cameron was cheered by Tory MPs as she crossed the floor of the House of Commons to sit on the Conservative benches

Dr Cameron (middle of top row) sat next to ex-prime minister Theresa May and Scottish Tory leader Douglas Ross as she joined the Tory side of the Commons chamber

Dr Cameron (middle of top row) sat next to ex-prime minister Theresa May and Scottish Tory leader Douglas Ross as she joined the Tory side of the Commons chamber

Dr Cameron sat on the Tory benches just prior to the start of Prime Minister's Questions this afternoon

Dr Cameron sat on the Tory benches just prior to the start of Prime Minister’s Questions this afternoon

Dr Cameron sat on the Tory benches just prior to the start of Prime Minister’s Questions this afternoon.

She stunned the SNP last week by announcing she was quitting the party and joining the Scottish Conservatives.

The 51-year-old blasted a ‘toxic and bullying’ environment within the SNP group at Westminster and revealed she had required counselling for 12 months.

‘I do not feel able to continue in what I have experienced as a toxic and bullying SNP Westminster group, which resulted in my requiring counselling for a period of 12 months in Parliament and caused significant deterioration in my health and wellbeing as assessed by my GP including the need for antidepressants,’ she said.

Rishi Sunak said he was ‘delighted’ Dr Cameron had joined the Tories and hailed her as a ‘brave and committed constituency MP’.

She has dismissed demands from SNP leader Humza Yousaf for her to trigger a by-election in her South Lanarkshire constituency.

‘Lisa Cameron should do the honourable thing, she should resign her seat,’ the Scottish First Minister said.

‘She should do the honourable thing by her constituents, who voted for an SNP MP, did not vote for a Conservative MP.

‘To see somebody who claims to have supported Scottish independence cross the floor to the Conservative and Unionist Party betrays the fact that she probably never believed in the cause in the first place.’

Dr Cameron’s defection came on the day she was facing a selection battle in her East Kilbride, Strathaven and Lesmahagow seat.

Her opponent in the selection race, Grant Costello, had received the backing of an SNP minister and she was not expected to win.

On Thursday afternoon, he was duly chosen as the SNP’s candidate for the next general election.

First elected as an SNP MP in 2015, Dr Cameron is a clinical psychiatrist who went on to win again in the two subsequent general elections.