Boris Johnson was presented with the “wrong crisis” as prime minister in coronavirus as he frustrated advisers by oscillating between decisions, the official inquiry has heard.

Mr Johnson dithered between wanting a lockdown and adopting his Mayor of Jaws “routine”, advocating keeping the country out of lockdown, the inquiry was told on Tuesday.

Lee Cain, his long-term adviser who served as No 10’s communications director in the pandemic, said Mr Johnson’s erratic decision-making was “rather exhausting”.

Messages between Mr Cain and Dominic Cummings, who served as the then-prime minister’s chief adviser, showed them venting their frustrations on WhatsApp.

“Get in here he’s melting down,” Mr Cummings wrote on March 19 2020, days before the first lockdown, adding that Mr Johnson was “back to Jaws mode wank”.

“I’ve literally said same thing ten f****** times and he still won’t absorb it,” he added.

Explaining the Jaws reference, Mr Cain told the inquiry that Mr Johnson would refer to the mayor from the Jaws film “who wanted to keep the beaches open”.

“I think he had a routine from previous in his career where he would use that as a joke from one of his after-dinner speeches,” he said.

“The mayor was right all along to keep the beaches open because it would have been a long-term harm to the community – so it’s a sort of sub-reference to that.”

Mr Cain was more cautious than Mr Cummings by avoiding saying their old ally was not up to the job as prime minister.

“I think at that point – and it’s quite a strong thing to say – what would probably be clear in Covid is it was the wrong crisis for this prime minister’s skillset,” Mr Cain said.

“Which is different, I think, from not potentially being up for the job of prime minister.”