Dominic Cummings has launched a renewed Twitter tirade in which he repeated claims the government had planned to let coronavirus spread through the country to build "herd immunity", despite ministerial denials.
The fresh social media broadside by the prime minister’s former top aide comes after Home Secretary Priti Patel insisted it had "absolutely not" been the original policy to develop COVID-19 resistance in the population.
However, speaking to Sky News last March, the government’s chief scientific adviser Sir Patrick Vallance said communities becoming immune to coronavirus was "going to be an important part of controlling this longer term".
He said at the time round 60% of the UK population would need to become infected in order for society to have "herd immunity" from future outbreaks.
At that early stage in the pandemic there was no vaccine available for coronavirus.
In his latest tweets, Mr Cummings wrote: "Herd immunity wasn’t ‘a secret strategy’, it was THE OFFICIAL PUBLIC EXPLAINED ON TV/RADIO STRATEGY!"
He also produced an image of what he claimed was a document from a Cobra emergency committee for last March, which explained the official thinking on "the advised herd immunity approach", which he said was described as "single peak optimal strategy".
In another post referring to the Health Secretary Matt Hancock and the Cabinet Office, he wrote: "In that week it became clear neither Hancock/CABOFF understood herd immunity effects: 100s of 1000s choking to death + no NHS for *anybody* for months + dead unburied + econ implosion; so we moved to Plan B: suppression + Manhattan Project for drugs/vaccines + test&trace etc."
However, striking an unusually conciliatory tone towards his former boss, he said in another tweet: "Critical as I am of the PM in all sorts of ways, it’s vital to understand the disaster was not just his fault: the official plan was disastrously misconceived, DHSC/CABOFF did not understand this or why, & a PlanB had to be bodged amid total & utter chaos."
He also took a sideswipe at Dr Jenny Harries, who was deputy chief medical officer for England at the time, after she insisted she had never been at a government meeting where herd immunity was discussed "as a mechanism of control".
Mr Cummings wrote: "Jenny Harries told us, the same week herd immunity was the official plan, masks are a ‘BAD idea’, ‘we don’t want to disrupt people’s lives’, acting ‘too early we will just pop up with another epidemic peak later’. So Whitehall has promoted her, obviously."
His posts came in apparent retaliation after Ms Patel rejected earlier claims by Mr Cummings that the government’s original response to the crisis was to pursue a strategy of "herd immunity".
Mr Cummings, who is due to give evidence this week to MPs investigating the government’s response to the pandemic, said there may have been no need for any lockdowns if the country had had the "right preparations and competent people in charge".
But pressed on the claim that herd immunity had been the original plan, Ms Patel replied: "Absolutely not."
She told the BBC: "Our strategy was always about protecting public health, saving lives and protecting the NHS.
"Absolutely all colleagues involved in those meetings and discussions, working with the chief scientist and the chief medical officers, absolutely recognised that from the very difficult discussions that we had.
"At the time of a crisis, when government is making very, very tough decisions, difficult decisions, we put public life and protecting the public at the forefront of all those decisions."
She was backed by Dr Harries, now chief executive of the UK Health Security Agency, who told the BBC: "I can categorically say I have never been in any government meeting where herd immunity was put forward at that point of the pandemic as a mechanism of control."
Downing Street is now braced for a potentially highly damaging onslaught from Mr Cummings on Wednesday following his acrimonious departure from No 10 at the end of last year.