This week at the COVID inquiry is about the advisers – the backroom officials now thrust into the spotlight.

They reveal new details of the chaotic decision-making in Number 10 – and more widely across government – and extremely candid assessments of the key players, but particularly Boris Johnson.

Today, Martin Reynolds, a close Johnson ally from his time at the foreign office who went to work as his principal private secretary, conceded that the former prime minister “blew hot and cold” on lockdown.

He insisted this was because of the momentous nature of the decisions. Messages from Simon Case, the most senior civil servant in government, are less charitable.

Politics latest: Government WhatsApp messages revealed during COVID inquiry

In one newly-released WhatsApp from late 2020, he says of Mr Johnson: “I’m at the end of my tether. He changes strategic direction every day.

“Monday, we were all about fear of virus returning as per Europe… today we were in ‘let it rip’ mode cos the UK is pathetic. He cannot lead and we cannot support him leading with this approach.”

In another message, he called the government a “terrible, tragic joke”.

Lee Cain, Johnson’s former director of communications, signalled his agreement with an emoji of a trolley – their nickname for the prime minister given his tendency, in their view, to veer from one side to another.

Sir Patrick Vallance, the former chief scientific adviser, described the prime minister in his diaries as “weak and indecisive” and constantly “flip-flopping”.

Later we heard from Imran Shafi, who worked in Number 10 advising the prime minister on public services.

He revealed a hand-scrawled note from a discussion between Mr Johnson and Mr Sunak in March 2020 which read: “We’re killing the patient to tackle the tumour… Why are we destroying economy for people who will die soon anyway?”

Asked who expressed these views, he said he thought it was Mr Johnson.

It would tally with claims that he talked to aides of letting the “bodies pile high” rather than allowing a second lockdown.

Dominic Cummings, once Mr Johnson’s closest ally but now his sworn enemy, told MPs he’d heard the former prime minister say it.

Mr Johnson and other senior politicians will be called by the inquiry by the end of this year.

Despite a court ruling that he must hand over WhatsApp messages from his old phone, used before April 2021, this process is not yet complete.

A spokesman for Mr Johnson said: “Boris Johnson is cooperating fully with the inquiry”.

Tomorrow, Mr Cummings, who has already spoken extensively on this, will be in front of the inquiry – no doubt to inflict further damage on his old nemesis.

And questions are also building up for Mr Sunak, who declared himself, while running for the Conservative leadership last year, to be sceptical of the lockdown.

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On Wednesday, Helen McNamara, the cabinet office official who called Sunak “Dr Death”, will give evidence.

And today, it was revealed that the cut-price meal scheme he championed as chancellor was dubbed “Eat Out to Help the Virus” by chief medical officer Chris Whitty.

For the current and former prime ministers, there could be plenty more unwelcome surprises.