Boris Johnson endured a testing time as Prime Minister last week as he contended with allegations of Downing Street Christmas parties and the largest Tory rebellion since 2019 in the House of Commons. The week was capped off when Lord David Frost stepped down as Brexit minister owing to concerns over the Government’s implementation of Covid measures. So, as reports emerge that stricter rules could be imminent, will any more Conservatives join Lord Frost in heading for the exit door?

       On Saturday, Lord Frost publicly announced his departure as Brexit minister, with immediate effect.

       The peer had originally planned to resign in January, but after news of his departure made it into the public domain, the decision was taken to bring forward his exit.

       Lord Frost had led negotiations with the EU on Brexit since January 2020.

       He will be succeeded by Liz Truss, the Foreign Secretary, who will fulfil both roles.

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       Speaking to reporters for the first time since the announcement was made, Lord Frost said he left his role as he could not support decisions made by the Government in relation to Covid restrictions.

       He said: "I left the Government, as I think is well known, because I couldn't support certain policies, most recently on COVID restrictions and 'Plan B'.

       "If you're a minister, you have to support collective responsibility, you have to support decisions of the Government, and I couldn't, so that's why I had to leave.

       "I don't support coercive policies on COVID. The Prime Minister's got some difficult decisions to take and I'm sure he'll be thinking very hard on them."

       Lord Frost’s departure raises questions as to whether more Tory MPs could follow his lead given that the Government is reported to be considering imposing stricter Covid measures.

       If no other restrictions are introduced beyond the current Plan B rules, the Scientific Advisory Group for Emergency (Sage) is warning hospital admissions could soon reach 3,000 per day.

       Advice to refrain from household mixing over the festive period - as has already been introduced in Scotland - is one of the measures Mr Johnson is said to be pondering.

       Social distancing and curfews for hospitality venues - such as pubs and restaurants - could also return to help combat the spread of the virus.

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       Last week, 100 Tory MPs voted against the PM’s rule to bring back NHS Covid passes for nightclubs and large events in a House of Commons vote.

       The rebellion represents the largest that has occurred since the 2019 General Election.

       Many of the MPs who voted against introducing NHS Covid passes had previously expressed concerns that the restriction would undermine public trust.

       Examples of MPs who voted against the PM’s rule included Iain Duncan Smith, Chris Grayling and Esther McVey.

       However, though discontent is visible within the Tory ranks, there are no suggestions any MPs will consider the same course of action as Lord Frost.

       Things could change quickly though if the Government were to implement further Covid rules.

       Indeed, as the UK’s ever-evolving Covid situation continues to escalate - 82,886 new daily cases reported for Sunday, December 19 - it appears action of some description from MPs is inevitable.