David Cameron criticises successor Theresa May over her management of Whitehall

David Cameron has accused Theresa May of making a “very bad mistake” by combining the role of National Security Adviser and Cabinet Secretary during her tenure.

The former prime minister heaped criticism on his successor, saying her decision in 2018 to hand both roles to one person, Sir Mark Sedwill, “temporarily weakened” Whitehall’s national security infrastructure.

“They are two jobs,” Mr Cameron said on Monday. “Even if you were a cross of Einstein, Wittgenstein & Mother Teresa, you couldn’t possibly do both jobs.”

The Cabinet Secretary is the most senior civil servant on Whitehall and is the senior policy adviser to the Prime Minister. The NSA is the central co-ordinator and adviser to the prime minister and cabinet on security, intelligence, defence, and some foreign policy matters.

The roles were split up again by Boris Johnson after he took office.

Addressing MPs and peers who sit on the Joint Committee on the National Strategic Security, Mr Cameron conceded it was a “mistake” that the Government’s future pandemic planning had focused on flu rather than respiratory diseases in the years leading up to the Covid-19 outbreak.

“I think there was a pretty good flu pandemic plan but it was a flu plan rather than a respiratory diseases plan,” he said. He also admitted that more lessons should have been learned from the SARS epidemic in 2004.

He questioned what had happened to a unit that he said was set up during his administration in the Cabinet Office to concentrate on “global virus surveillance”.

Mr Johnson is now pushing for an international version of such a unit. He has called on global leaders to join a “global pandemic early warning system to predict a coming health crisis”, part of his five-point plan for curbing future pandemics.

It would require “a vast expansion of our ability to collect and analyse samples and distribute the findings, using health data-sharing agreements covering every country”, the Prime Minister has said.

Mr Cameron ruled out returning to the political arena when asked on Monday whether he would consider a comeback. “No,” he said. “Thinking about Donald Trump making a comeback is enough to keep us all spinning over.”

He added that he was “happy doing what I’m doing for Alzheimer’s and dementia” and highlighted a fragile states council he has set up with former Liberian and Rwandan ministers.

Asked whether he missed being prime minister, he quipped that he did not miss Wednesdays at noon, the time at which he faced his weekly Commons showdown with the Leader of the Opposition during Prime Minister’s Questions.

Mr Cameron seized the opportunity to restate his criticism of Mr Johnson for axing the Department for International Development (DfID), branding it another “mistake”.

“Having the Foreign Office voice around the (National Security Council) table and the DfID voice around the table I think is important,” Mr Cameron said.

He added: “Can you really expect the foreign secretary to do all of the diplomatic stuff and be able to speak to the development brief as well? That's quite a task, so I think it is good to have both.”