Contact tracers are descending on Parliament today after an SNP MP flouted self-isolation rules to attend the Commons.
Margaret Ferrier is facing universal condemnation for her 'utterly indefensible' behaviour in going to Westminster while suffering symptoms - and then taking a train back to Scotland after her test was positive.
The flagrant breach of quarantine law is punishable with a £4,000 fine, and Ms Ferrier is also being urged by her own colleagues to resign as MP for Rutherglen & Hamilton West.
The SNP's Westminster leader Ian Blackford, who has already stripped her of the whip, said this morning that she must 'reflect on her position'. 'I think it is obvious what she needs to do,' he told BBC Breakfast.
The Commons said one person who had come into contact with Ms Ferrier had been told to self-isolate, with investigations into who else might be at risk set to continue. Extra cleaning precautions have also been taken - although the damage might already have been done.
Astonishingly, the 60-year-old received a positive result on Monday night and still appeared in the Commons chamber (pictured), speaking in a debate on coronavirus and its impact on the economy and jobs
Her own leader, Scottish First Minister Nicola Sturgeon, branded her MP's actions 'utterly indefensible' and said it was hard to express 'how angry' she felt
'I apologise unreservedly for breaching Covid-19 restrictions by travelling this week when I shouldn't have. There is no excuse for my actions.
'On Saturday afternoon, after experiencing mild symptoms, I requested a Covid-19 test which I took that day. Feeling much better, I then travelled to London by train on Monday to attend Parliament as planned. This was wrong, and I am very sorry for my mistake.
'On Monday evening I received a positive test result for Covid-19. I travelled home by train on Tuesday morning without seeking advice. This was also wrong and I am sorry. I have been self-isolating at home ever since.
'I have used Test and Protect and I have notified the House of Commons authorities who have spoken with Public Health England. I have also notified the police of my actions.
'Despite feeling well, I should have self-isolated while waiting for my test result, and I deeply regret my actions. I take full responsibility and I would urge everyone not to make the same mistakes that I have, and do all they can to help limit the spread of Covid-19.'
SNP leader Nicola Sturgeon condemned the MP's 'utterly indefensible' behaviour and welcomed her having the whip suspended, but there were calls for Ms Ferrier's resignation including from within the party.
The Rutherglen and Hamilton West MP said she took a test on Saturday afternoon after experiencing 'mild symptoms', meaning she should have self-isolated, before travelling by train to London on Monday having felt better.
Labour suggested the party covered up knowledge of Margaret Ferrier's actions after it emerged they knew of her diagnosis a day before she disclosed it on Thursday evening.
She spoke in the coronavirus debate in the House of Commons on Monday and, by her account, tested positive for Covid-19 that evening. She did not make clear whether she received the result before or after she spoke.
In a statement, she said she travelled home to Glasgow on Tuesday, where she has been self-isolating ever since.
Police Scotland said the MP informed them of her behaviour on Thursday and officers are 'looking into the circumstances' along with the Metropolitan Police.
The Commons said she did not inform her party whip until Wednesday afternoon and that one person was identified as a close contact and told to self-isolate.
Ms Ferrier could face a £4,000 fine for a first-time offence of coming into contact with others when she should