Boris Johnson has addressed a group of Tory MPs representing northern constituencies from his self-isolation as he seeks to unite the party and prevent backbench rebellions.

The Prime Minister held a video call with around 60 MPs from the Northern Research Group (NRG), which formed over concerns lockdowns were damaging the North of England.

The call came as Health Secretary Matt Hancock was unable to guarantee the national shutdown would end on December 2 as he stood in for Mr Johnson at the Downing Street press conference.

Public Health England’s Dr Susan Hopkins also said the restrictions in the three-tiered system that the Prime Minister hopes to return to may have to be strengthened.

Mr Johnson was understood to have spoken to the NRG for around an hour in a call from No 10 where he is isolating after coming into contact with an MP who tested positive for Covid-19.

He thanked them for forming the group and insisted their agenda would be “central” to his Government’s plans, in words that were welcomed by many of the participants.

The group, led by former northern powerhouse minister Jake Berry, had been expected to press him to detail a “clear route out of lockdown” to prevent further damage to their communities.

A statement from the NRG said: “The Prime Minister’s enthusiasm to meet with the NRG, despite being in self-isolation, demonstrates his determination to ensure the North is at the heart of this Government’s agenda and his ambition to ‘level up’ our communities remains a priority.

“The NRG is committed to working constructively with the Prime Minister to level-up our communities and to build back better out of this Covid crisis.”

Along with the pandemic, Mr Johnson is dealing with the final weeks of post-Brexit trade negotiations with the EU and in-fighting in No 10 that led to the departure of his chief aide, Dominic Cummings.

He is trying to “reset” his premiership amid the turmoil and is trying to ward off any further rebellions within his party.

Earlier this month, 32 Tory MPs defied the whip to vote against the second lockdown for England, which the Government succeeded in passing along with Labour support.

Another 17 Conservatives, including former prime minister Theresa May, abstained from the vote, with backbenchers expressing alarm at the economic impact of the controls and the curtailment of personal liberties.

Various factions within the party have formed pressure groups to sway Mr Johnson’s thinking, including the “Covid recovery group” to resist further lockdowns.

The four-week lockdown for England expires on December 2 and the Prime Minister has promised MPs a vote on the measures that replace it.

Mr Hancock sounded less confident than his leader that the severe restrictions will be eased.

“It is too early for us to know what the number of cases will be as we come to the end of the current lockdown,” Mr Hancock told the press conference.

“But we absolutely hope to be able to replace the national lockdown with a tiered system similar to what we had before.”

Dr Hopkins said the Tier 1 coronavirus restrictions had “little effect” while the impact of Tier 2 varied in different places, and suggested they may have to be strengthened during the winter.

The Prime Minister, while feeling “fit and well”, is self-isolating for 14 days because of a notification from NHS Test and Trace after Ashfield MP Lee Anderson tested positive for Covid-19.

At least nine other Conservative MPs have also entered quarantine.