Gavin Barwell, former No 10 chief of staff, said Mr Sunak was wrong to take legal action against the Covid inquiry because it had invited suspicion about the government’s true motives for protecting the messages.
“The sense you get is Boris is enjoying this – enjoying making life more awkward for Sunak,” Lord Barwell told The Independent.
Johnson allies have claimed that Mr Sunak was refusing to hand over messages due to fears they could show plots against the former prime minister or embarrassing details about the ex-chancellor’s Eat Out to Help Out scheme.
One Johnson ally told the Mail on Sunday: “What is Rishi hiding? Is it plotting against Boris with Dominic Cummings? Is it because he himself broke lockdown rules? Or does he fear that his Eat Out to Help Out scheme led to a significant number of deaths?”
Lord Barwell, Theresa May’s former chief of staff, dismissed the Johnson camp’s “psychodrama”, but added: “Whether there is something in the WhatsApps that Johnson knows will be embarrassing for Sunak, I don’t know.”
The Tory peer said he believed the government legal action was “driven by the civil servants as much as the politicians” – but warned that the perception that Mr Sunak and other ministers may have something to hide was damaging.
“It’s not a great look for the government, clearly,” said Lord Barwell. “If you think about those lost loved ones, it’s not going to instil confidence in them.
“And for some lockdown sceptics, people like [broadcaster] Julia Hartley-Brewer, they may say it confirms it’s all an establishment stitch-up. So if it increases scepticism, it’s quite damaging.”
The senior Tory added: “It seems a political error to get into this row. The best way for Sunak to handle it is to provide the inquiry with what it needs. Trust the inquiry chairwoman [Lady Hallett] and let her get on with it.”
Robert Kerslake, the former head of the civil service, has also warned that the furore was ripe for exploitation by Mr Johnson – who raised the stakes on Friday by turning over unredacted messages from May 2021 directly to Lady Hallett’s team.
The former cabinet secretary told The Independent: “It’s turning into an internal wrangle within the Conservative Party. Boris may well see it as a way of creating a divide line between him and Sunak – it could work to his advantage if Sunak is seen to be the one blocking.”
As the row escalated, a Whitehall source told the Mail on Sunday: “The government has taken a judge to court to keep other ministers’ messages secret. Why? What is team Sunak trying to hide? The cover-up office is a shambles and it’s only a matter of time before heads roll.”
But a source close to Mr Sunak told The Independent: “It’s total rubbish – as you can see from the Telegraph’s lockdown files, Rishi Sunak barely uses WhatsApp.”
Asked about the claims by Johnson allies and whether Mr Sunak was trying to hide plots against Mr Johnson, immigration minister Robert Jenrick told Sky News: “No – the issue here is … should you hand over material to the inquiry which has absolutely nothing to do with Covid.”
Mr Jenrick said it is not “sensible or reasonable” to share material unrelated to Covid – and suggested a compromise was still possible, despite the judicial review. “I hope this can be resolved indeed even before the matter gets to court,” he added.
The latest row comes as it emerged that Cabinet Office lawyers told Mr Johnson that taxpayer-funded legal support would “cease to be available” if he breaks conditions such as releasing evidence without permission.
The former PM vowed to send all his messages to the official investigation directly, circumventing the Cabinet Office. The Sunday Times detailed a letter sent by Cabinet Office lawyers to Mr Johnson warning he could lose legal support if he tries to “undermine” the government’s position.
Mr Jenrick told Sky’s Sophy Ridge on Sunday that Mr Johnson was still “at liberty” to do as he wished. “There’s absolutely no sense that the government will restrict what Boris Johnson wants to say – but if you use taxpayer funds, obviously you should make sure you’re using them appropriately.”
The dispute escalated as a lawyer representing the bereaved families warned that the cost of the judicial inquiry launched by the Sunak government could be around £500,000.
Elkan Abrahamson, a solicitor who is representing the Covid bereaved families group, told The Independent that the cost of the government’s legal action could run “well into the six figures”.
Based on previous judicial reviews he has been involved in, where the cost of single application firms can be £30,000, Mr Abrahamson said. “If you cost in judicial time, and Johnson’s bill if he were joined in the proceedings, it could get to £500,000.”
Mr Sunak is under increasing pressure over his own role in key Covid-era decisions, such as the Eat Out to Help Out to boost the hospitality sector after the first lockdown.
Prof John Edmunds of the London School of Hygiene and Tropical Medicine – a member of the government’s Sage committee – said Eat Out to Help Out was “a spectacularly stupid idea and an obscene way to spend public money”.
The former adviser told The Observer the August 2020 scheme to offer Britons a discount to eat out in restaurants and pubs was never discussed with scientists.
The Covid-19 Bereaved Families for Justice UK group told The Independent that Mr Sunak should stop trying to “protect himself” and hand over his own WhatsApps so crucial pandemic decisions – including the Eat Out to Help Out scheme – can be scrutinised.