CHANNEL 4’s Dispatches produced new evidence that Boris Johnson was pursuing a crackpot “herd immunity” strategy against coronavirus, which the government has again denied.

This just adds to the herd immunity evidence, some of which is very public.

There is in fact also evidence of the herd immunity plan in the recently released papers of the government’s Scientific Advisory Group for Emergencies (Sage), which has been generally overlooked.

Dispatches says that on March 13 Johnson spoke to Italian Prime Minister Giuseppe Conte about the coronavirus crisis — at that time Italy was in lockdown, with Spain and France soon to follow.

Italy’s health minister says that after this call he spoke to Conte and “he [Conte] told me that he [Johnson] wants herd immunity.”

Responding to the documentary, the Department of Health said: “The government has been very clear that herd immunity has never been our policy or goal.”

The herd immunity strategy is to let the virus rip among all but the most vulnerable, so that people become ill, but then recover and become immune.

The formerly-ill-now-immune can then care for the most vulnerable groups and keep society running.

It’s a kind of “laissez-faire” or semi-Darwinian approach that appeals to some on the right.

However, if death rates for coronavirus approach anything like 1 per cent, then it could imply around 500,000 deaths: because of this, the government has repeatedly denied it had a herd immunity strategy, despite evidence that it did.

So on March 13 government chief scientific adviser Patrick Vallance told Radio 4’s Today programme that government policy was protecting the most vulnerable and reducing the outbreak “peak.”

However, he argued that because most people only got a “mild illness,” allowing a slow spread would let them “build up some kind of herd immunity.”

David Halpern, a psychologist and businessman who was invited to sit on Sage, also referred to “herd immunity” at the same time.

Halpern set up a government group, the Behavioural Insights Team, also known as the “Nudge Unit,” which was then privatised.

His Nudge Unit sells policy solutions to governments which supposedly use psychological techniques to create clever but low-cost social interventions.

Health Secretary Matt Hancock rejected Vallance and Halpern’s statements, saying: “Herd immunity is not our policy. It’s not our goal.”

However, as well as Vallance and Halpern’s statements, Sage papers show there was discussion of herd immunity, although the herd immunity enthusiasts could not win backing for the plan.

The Labour opposition pressured Johnson into releasing the papers from Sage, to show what actual scientific advice the government had received.

These papers show the Sage discussion of herd immunity.

A February 26 Sage paper, written by a subcommittee called SPI-M-O says one strategy “would be to apply more intense measures on those age or risk groups at most risk of experiencing severe disease,” including “household isolation” for over-65s and “special measures around care homes.”

Meanwhile “the majority of the population would then develop immunity.”

This is Vallance’s herd immunity plan, but the paper says the scientific group “has not looked at the likely feasibility or effectiveness of such methods.”

A paper for the March 5 Sage meeting from another subcommittee, called SPI-B says scientists have “divergent opinions” on a plan to only impose isolation on “at-risk” groups while allowing everybody else to start “building some immunity.”

Again, the herd immunity plan was discussed, but not supported by all.

On the same day that Sage refused to support herd immunity, Johnson himself appeared to at least partly support it: he said on ITV’s This Morning that “one of the theories is, that perhaps you could take it on the chin, take it all in one go and allow the disease, as it were, to move through the population, without taking as many draconian measures.”

Johnson said he would “strike a balance” between this and trying to “stop the peak of the disease.”

Government reluctance to go into lockdown suggests it was drawn to the “herd immunity” plan because it involved doing least, only dropping it when it realised the potential scale of death involved.

While the Sage papers show that the scientific advisers discussed but rejected herd immunity, they also show that Sage did not have a very strong alternative.

Sage papers show that by February 17 Sage thought the potential loss of life was very great: they estimated an unchecked coronavirus epidemic would probably mean “around 80 per cent of the population becoming infected.”

On February 26 Sage made its first estimate of the infection fatality rate, which it put at roughly 1 per cent. It feared hundreds of thousands of lives were at risk in an unchecked epidemic.

However, Sage papers also generally showed the advisers did not believe that fully stopping the virus was possible: they were not impressed by attempts on mainland China or Hong Kong or Singapore to completely check infection by “contact tracing,” hygiene and isolation.

Instead, as early as February Sage advisers were saying that because the “NHS will be unable to meet all demands” from an unchecked pandemic, measures should be taken to “delay” and “reduce the size of the peak” of infection.

Some Sage papers recommended some combination of strong measures back in February, including “closure of schools” and “social distancing for 13 weeks, when enacted early.”

However, the main Sage committee, with people like Halpern, Vallance and Cummings present, were able to drag their feet on lockdown and reject full national contact tracing as a means to stop the pandemic, even if Sage could not be persuaded to back herd immunity.