Another Cabinet minister has entered self-isolation over coronavirus after Boris Johnson and Health Secretary Matt Hancock tested positive for Covid-19.
Scottish Secretary Alister Jack said on Saturday that he would be following guidance and staying at home after developing mild symptoms, although he has not been tested.
The Prime Minister is continuing to command the response to the pandemic from Downing Street after he was diagnosed with the disease.
He has been accused of failing to follow his own social distancing rules after Mr Hancock tested positive and their key lieutenant Professor Chris Whitty began self-isolating with symptoms.
The PM is likely to face further criticism after Mr Jack, the Conservative MP for Dumfries and Galloway, followed them into isolation.
Mr Johnson sat next to Mr Jack as he took Scottish questions at the despatch box in the House of Commons on Wednesday, immediately before Prime Minister's Questions.
Mr Hancock was to the Scottish Secretary's other side on the front bench.
On Saturday, Mr Jack announced he had developed a mild temperature and a cough "in the past 24 hours" and would continue working from home.
He had travelled back to his constituency as Parliament closed because of the pandemic on Wednesday.
Other key figures will be increasingly wary of developing symptoms after the virus struck at the heart of Government.
It is highly likely that Prof Whitty, England's chief medical officer, will be awaiting results of his own test for the virus.
The 55-year-old Prime Minister, who had a high temperature and persistent cough, is continuing to lead efforts to slow the virus's spread from his flat above No 11 Downing Street.
Concerns are rife over which other key figures could be affected, with Chancellor Rishi Sunak having been with the PM shortly before he tested positive.
Cabinet Secretary Sir Mark Sedwill was also with Mr Johnson, Mr Hancock and Prof Whitty at a Cabinet meeting on Tuesday.
Neither the Chancellor nor Sir Mark had displayed symptoms by Friday night so they had not been tested and were not in isolation.
The PM and Mr Hancock were only showing "mild symptoms" but would have to spend seven days in isolation.
Mr Johnson noticed symptoms on Thursday afternoon before receiving test results at midnight.
At the latest of the Government's daily press conferences, Cabinet minister Michael Gove declined to be drawn on whether MPs had been too slow to practise social distancing.
He just said the diagnosis of Mr Johnson and Mr Hancock showed the "virus does not discriminate", warning: "We are all at risk."
By Mr Gove's side, NHS England chief executive Sir Simon Stevens said testing would begin on NHS staff for coronavirus from next week, following widespread concern.
He also announced that he had given the go-ahead to two new temporary hospitals being built in Birmingham and Manchester to join a facility under development in London.