UK Prime Minister Boris Johnsons former top aide Dominic Cummings, who had an unceremonious exit from Downing Street last year, has claimed that his ex-boss was reluctant to tighten restrictions as Covid-19 cases rose last September because he thought people dying were "essentially all over 80".

Cummings, who has made a series of attacks on the Prime Minister over his handling of the Covid-19 pandemic lockdown in the country, launched a fresh set of allegations in an interview to the BBC.

He said that Johnson had messaged him to say: “I no longer buy all this NHS (National Health Service) overwhelmed stuff.”

Cummings said that Johnson was reluctant to tighten Covid-19 restrictions as cases rose last September because he thought people dying from it were “essentially all over 80”.

In response, Downing Street said the Prime Minister had taken the "necessary action to protect lives and livelihoods, guided by the best scientific advice" throughout the pandemic.

Cummings told the BBC that he, UK Chief Scientific Adviser Sir Patrick Vallance and England's Chief Medical Officer Professor Chris Whitty had pushed for tougher restrictions from mid-September, but Johnson had said: "No, no, no, no, no, I'm not doing it."

In a wide-ranging television interview, Cummings said near the start of the pandemic last year, Johnson had wanted to keep his weekly face-to-face meetings with the Queen going but that he had to warn his boss that she might die if she caught coronavirus.

"There's people in this office who are isolating. You might have coronavirus. I might have coronavirus. You can't go and see the Queen. What if you go and see her and give the Queen coronavirus? You obviously can't go," he claims to have said.

He continued: "I just said, 'If you give her coronavirus and she dies, what are you going to (do)? You can't do that. You can't risk that. That's completely insane.' And (the PM) said - he basically just hadn't thought it through - 'Yeah...I can't go'."

Downing Street denied that this incident took place and Buckingham Palace declined to comment.

A Downing Street spokesperson said: "Since the start of the pandemic, the Prime Minister has taken the necessary action to protect lives and livelihoods, guided by the best scientific advice.

"The government he leads has delivered the fastest vaccination rollout in Europe, saved millions of jobs through the furlough scheme and prevented the NHS from being overwhelmed through three national lockdowns. The government is entirely focused on emerging cautiously from the pandemic and building back better."

Cummings, in his previous outpourings on Twitter, his online blog and before a parliamentary committee, has made a series of withering attacks on his former boss and declared that the government had fallen disastrously short in its response to the COVID-19 pandemic.

As one of the architects of the successful Brexit campaign that resulted in Britain's exit from the European Union (EU) in the June 2016 referendum, Cummings went on to become one of Johnson's closest allies and followed him to Downing Street.

He is also credited with Johnson's landslide general election win in December 2019. However, he left his position in November last year and was pictured leaving 10 Downing Street with a box in hand indicative of an unceremonious exit after a much-publicised power struggle within the top ranks of the Prime Minister's office.