Dominic Cummings has said Downing Street is dominated by “the blind leading the blind” and if the public could see how decisions were made, “everyone would sell everything and head for the bunker in the hills”.

The Prime Minister’s former chief adviser used an online question and answer session on Monday to unleash a fresh salvo of criticism at the Government. It built on a wave of attacks launched since he left Number 10 in the wake of a bitter power struggle last November.

He derided Number 10 as “just a branch of [the] entertainment industry” and also heaped criticism on the Tory party as “hideous”. Elsewhere he claimed: “All the parties are rotten to the core, old decrepit entities literally dying on their feet.”

The crop of mandarins at the helm of Whitehall departments when he entered the Government were “shockingly bad” and peppered by an “incredible number of utter duffers”, Mr Cummings claimed, adding: “We cleared some out but still…”

He heaped scorn on Whitehall’s “appalling” record on science and technology in recent decades, which he claimed was “a big part of our problem with productivity, education, and defence procurement”.

Boris Cummings timelines

Sir Keir Starmer was meanwhile branded “just another not great lawyer” who is “content to fail in all the usual ways”. Labour should aim to “kick Tories up and down the street on violent crime”, suggested Mr Cummings, but he added: “Starmer is fixated on media/bubble, he won’t reorient to public.”

The barrage of condemnations came in response to hundreds of reader questions, after Mr Cummings urged subscribers to his new £10-a-month newsletter, hosted on the platform Substack, to “ask me anything”.

Alongside his wide-ranging denunciations, he commented on the Government’s handling of the coronavirus epidemic and highlighted the use of “do not resuscitate” (DNR) orders, after their inappropriate use on patients with learning disabilities was exposed by The Telegraph.

Asked whether there had been conversations about DNR notices being deployed in a blanket fashion on such groups, he said: “Not in front of me… But I think this whole issue does need urgently addressing now, clearly some terrible stuff happened.”

Another reader quizzed him on what it was like to be close to power, to which he replied: “Fascinating but very troubling… When you watch the apex of power you feel like ‘if this were broadcast, everyone would sell everything and head for the bunker in the hills’.”

He continued: “It’s impossible to describe how horrific decision-making is at the apex of power and how few people watching it have any clue how bad it is or any sense of how to do it better, it’s generally the blind leading the blind with a few non-blind desperately shoving fingers in dykes and clutching their heads…”

Mr Cummings suggested that Mr Johnson would eschew focusing on issues like the international race to develop artificial general intelligence (AGI), which he warned could “destroy us all”.

AGI could “easily be much worse than even total nuclear war” and “ought to be a massive focus of government thinking but it is not”, he said.

The latest shots fired in his sustained assault on his former boss and ally came after he called Mr Johnson a “gaffe machine” on Twitter last week and released personal texts that showed the Prime Minister had described Matt Hancock, the Health Secretary, as “totally f—— hopeless” during the early phase of the pandemic last year.

Asked on Monday whether he had any additional material to underpin his unsubstantiated allegations against Mr Hancock, whom he has repeatedly accused of dishonesty, Mr Cummings evaded answering, leaving open the door to the publication of further documents or messages.

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The ex-aide claimed that “people don’t seem to realise that lots of people will swear under oath what I’ve said about Hancock is true!” and accused the Health Secretary of saying “nonsense things all the time”.

Mr Hancock has said the claims against him are “not true” and that he and Mr Johnson work “very strongly together”.

Mr Cummings admitted that in the past he “screamed at the PM a few times” as he exhorted him to ignore the media.

In another barb, he claimed that Mr Johnson was “not that interested” in the Union, unless there was media scrutiny or “immediate pressure”.

Harking back to his time in Number 10, Mr Cummings said he had devised a plan to overlook MPs for crucial Cabinet posts and instead appoint “executive figures” from industry.

He said: “Our constitution is flexible enough to do this as we showed putting [Kate] Bingham in charge of vaccines – the PM cd [could] pick who they want, shove em [them] in Lords if you want, there’s no constitutional requirement for ministers to be MPs…

“I intended to try a big move in this direction straight after [the] election. Obviously Covid intervened though I think Boris wdn’t [wouldn’t] have dared do it anyway”.

Many of the reader questions put to him touched on Brexit and his role leading the Vote Leave campaign ahead of the EU referendum.

He claimed that he “never thought trade deals much important”, adding that he disagreed with Brexiteer MPs at the time over whether free trade agreements would be a benefit of leaving the bloc.

He said that he thought Mr Johnson’s vision for a post-Brexit Global Britain was “a c–p slogan that five years later still means nothing”.