WhatsApp exchanges released earlier this week showed that the Prime Minister proposed a “Great Exhibition 2.0” when speaking with Lord Brownlow, who he was asking for help with the £112,000 refurbishment of the Downing Street flat.

That conversation led to a meeting between the Conservative peer and then-culture secretary Oliver Dowden but the idea, as Lord Brownlow envisaged, was not progressed.

Now, the opposition say they have asked Standards Commissioner Kathryn Stone to investigate the correspondence, believing there may be questions to answer over “cash for access”.

Prime Minister Boris Johnson during a visit to a vaccination centre earlier this week (PA)

Shadow Justice Secretary Steve Reed said the text messages “matter immensely”, arguing that they show Lord Brownlow “appears to have access to the Prime Minister because he was paying for the flat renovations” at Downing Street.

“If that is the case, that is corruption,” he told BBC Radio 4’s Today programme.

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In a WhatsApp message sent on November 29 2020, Conservative Party leader Mr Johnson asked Lord Brownlow if he would give his approval for interior designer Lulu Lytle to begin work.

He added: “Ps am on the great exhibition plan Will revert.”

The peer said he would sort the flat “ASAP”.

He added: “Thanks for thinking about GE2”.

On January 18 2021, Lord Brownlow attended a meeting with Mr Dowden and representatives of the Albert Hall to discuss the peer’s Great Exhibition 2.0 proposal.

A spokesman for the Prime Minister said the Tory peer’s suggestion was “dealt with in the same way” as a member of the public’s would have been “in that a department will look at it and take a view on it”.

Labour asks Parliamentary standards commissioner to investigate texts between PM and Tory donor