Downing Street cleaners and security staff have been subjected to a “lack of respect and poor treatment”, the likes of which they felt “unable to raise properly”, Sue Gray’s report into the Partygate scandal has revealed.

       The damning revelation was revealed in the report that looked into lockdown-busting parties held in the heart of government. It was published in full on Wednesday after a heavily-redacted version was released in January while the Metropolitan Police carried out its own probe into events.

       The findings of the inquiry, first launched in December, were made public by No 10 just before Boris Johnson met MPs in the Commons today’s round of Prime Minister’s Questions.

       Among the cataloguing of No 10’s boozy culture - of plucky junior civil servants following the lead of their more senior colleagues in attending the drunken events - are ruinous descriptions of the concerns of Downing Street’s cleaners and security staff being dismissed.

       Many of those workers are paid substantially less than the partygoing government staffers.

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       In the conclusion of her report, Ms Gray states: “I found that some staff had witnessed or been subjected to behaviours at work which they had felt concerned about but at times felt unable to raise properly.

       “I was made aware of multiple examples of a lack of respect and poor treatment of security and cleaning staff.

       “This was unacceptable. I am reassured to see that steps have since been taken to introduce more easily accessible means by which to raise concerns electronically, in person or online, including directly with the permanent secretary in No 10.

       “I hope that this will truly embed a culture that welcomes and creates opportunities for challenge and speaking up at all levels.”

       Addressing MPs in the Commons, prime minister Boris Johnson offered a stoney-faced apology to the security and cleaning staff for their “appalling” treatment

       He insisted he had “no knowledge” of such treatment, saying he was “surprised and disappointed” to hear about them.

       He told the chamber: “I have been as surprised and disappointed as anyone else in this House as the revelations have unfolded and, frankly, I have been appalled by some of the behaviour, particularly in the treatment of the security and the cleaning staff.

       “And I’d like to apologise to those members of staff and I expect anyone who behaved in that way to apologise to them as well.”

       Referring to Ms Gray’s report, deputy Labour leader Angela Rayner tweeted: “Boris Johnson has turned Downing Street into a vomit-stained Bullingdon Club.

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       “The treatment and mockery doled out to cleaning and security staff that has now been exposed is beyond shameful.

       “This prime minister has nothing but contempt for the people of this country.”