Downing Street staff were advised to “clean up” their phones by removing information that could suggest lockdown parties were held at No 10, The Independent has been told.

       Two sources claim a senior member of staff told them it would be a “good idea” to remove any messages implying they had attended or were even aware of anything that could “look like a party”.

       Boris Johnson is facing an internal investigation into lockdown-breaching parties, being carried out by senior civil servant Sue Gray, and fury at revelations that 100 Downing Street workers were invited by email to a drinks event on 20 May 2020, when Britons were allowed to meet only one other person outdoors.

       Deputy Labour leader Angela Rayner said it raised “yet more questions for a prime minister who seems to have no answers”.

       The “clean-up” suggestion was made early last month after the first reports emerged of parties at Downing Street, the sources allege.

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       One said they were “told to clean up their phone just in case” they had to hand it in to the investigation.

       A second said: “I was being leant on [during the discussion with a senior colleague] and told to get rid of anything that could look bad.”

       Both sources told The Independent they felt under pressure to delete communications and images.

       The claims that a senior member of staff directed junior colleagues to remove potential evidence contradicts an email, also sent in December, that instructed staff not to destroy any material that could prove pertinent to an investigation, criminal or otherwise.

       This was meant to refer to emails, WhatsApp messages, and calendar invitations, but it was allegedly not observed by some staff, many of whom conducted discussions via WhatsApp on their personal phones as well as work devices.

       Personal phones cannot be accessed by Ms Gray’s investigation unless staff volunteer them. However, staff can be forced to hand over workplace handsets.

       With many staff who attended lockdown-busting events no longer working at No 10, and others having wiped messages from their phones, it will be hard for Ms Gray to gather all available evidence of wrongdoing, sources claim.

       Emails at No 10 are automatically deleted after 90 days for security reasons. This is also the case in some other sensitive government departments but not all.

       Ultimately, deleted emails can be recovered from servers, but this is far more challenging than accessing historic messages in some other departments, according to people familiar with the process.

       Lord Evans of Weardale, chairman of the Committee on Standards in Public Life, said civil servants should remember that all messages that are relevant to government business ought to be retained and recorded.

       A No 10 spokesperson told The Independent that they did not recognise the claims.

       “Staff were given clear guidance to retain any relevant information. As set out in the terms of reference, all staff are expected to fully co-operate with the investigation,” the spokesperson said.

       Ms Rayner said: “The latest revelations about this scandal raise yet more questions for a prime minister who seems to have no answers.

       “From missing minutes to secret WhatsApp messages, a culture of cover-up is endemic in Boris Johnson’s No 10 and the rot starts at the top.

       “The prime minister has a habit of trying to dodge scrutiny, but the consequences are catching up with him. The public deserve to know the truth about what went on while they were making so many sacrifices to obey the rules.”

       Liberal Democrat Home Affairs spokesperson Alistair Carmichael said: “Destroying evidence for what may soon be a police investigation is an incredibly serious offence.

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       “No wonder the public has lost all faith in Boris Johnson’s Downing Street. This would be a new low, even for his government.

       “Sue Gray must ask all those involved if they have been pressured or ordered to delete messages and emails relating to any parties. If a cover-up took place, then it must be exposed and all details made public. There should be no more hiding or lying from this prime minister.”