But the prime minister stopped them answering questions, claiming: “It is very important that our advisers are protected from being dragged into political controversy.”
The extraordinary ban came hours after Durham Police made clear their belief that Mr Cummings did commit an offence on his day trip to Barnard Castle, after leaving London for Durham.
The verdict has reignited the furore over Mr Johnson’s chief aide – even as he told the daily briefing that he would now “draw a line under the matter”.
The chief medical officer and chief scientific adviser were asked whether they believed Mr Cummings had set a good “example” to the public, in driving across the country when Covid-19 infection was suspected.
A later question asked whether the pair would “advise a 60-mile trip to test your eyesight” – the defence given by the aide for his trip to the beauty spot.
Tim Farron, the former Liberal Democrat leader, was among those to express his disbelief, tweeting: “Blimey! Gagging the experts in the midst of a pandemic!
“What has Britain done to deserve such incompetent and mendacious leadership just when it needed the opposite?”
Angela Rayner, Labour’s deputy leader, accused the prime minister of “Trumpesque” behaviour”, including stopping any follow-up questions from journalists.
“The PM blocking questions to Vallance and Whitty for their view on Cummings is completely wrong and the public will draw their own conclusions on it,” she said.
However, both experts appeared to be relieved not to be put on the spot, prompting suggestions they had only agreed to appear if they were shielded from the subject.
Professor Whitty, the chief medical officer, said: “The desire to not get pulled into politics is far stronger on the part of Sir Patrick and me than it is in the prime minister.”
And Sir Patrick, chief scientific adviser, added: “I’m a civil servant, I’m politically neutral, I don’t want to get involved in politics at all.”
Mr Johnson, meanwhile, denied the public would reject his coronavirus restrictions because of his aide’s behaviour, as he announced the next stage of easing lockdown.
“No, I don’t think that people will respond differently, I think people will listen very carefully to what the messages are,” he insisted.
Durham Police said Mr Cummings “might” have committed a breach that required further action.
The force had made clear that, if he had been stopped on his journey to Barnard Castle, he would have been told to return to Durham, underlining the belief that an offence was committed.
When Prof Whitty and Sir Patrick were asked to give their views, the prime minister stepped in and said: “I know that you’ve asked Chris and Patrick but I’m going to interpose myself if I may and protect them from what I think would be an unfair and unnecessary attempt to ask any political questions.
“It’s very, very important that our medical officers and scientific advisers do not get dragged into what I think most people would recognise is fundamentally a political argument.”
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