Almost one fifth of MPs – 123 in total - let out at least one property to boost their income, new research by Channel 4 reveals.

The MPs include chancellor Philip Hammond, foreign secretary Boris Johnson, the shadow foreign secretary Emily Thornberry, and the Speaker of the House of Commons, John Bercow.

But Channel 4’s FactCheck research service admits that the figure may not be 100 per cent accurate as there is no definite check on the MPs’ register of interests so it is presumed that members are declaring honestly.

It is not illegal for an MP to not declare a financial interest, and MPs are only asked to declare properties which they earn more than £10,000 a year from. Because finances change, the figures only provide a snapshot.

The issue has sparked an outcry in the wake of the Grenfell Tower tragedy, with critics saying that having a financial stake in the rented property sector could be a conflict of interests.

New MP Laura Pidcock has said: “I think that anyone who is a landlord should not be able to vote on legislation affecting landlords, it is a complete conflict of interest.

“The people of Grenfell Tower have had their concerns repeatedly ignored and it is part of our long history as working class people to have our concerns ignored.”

Under the declared figures, some 28 per cent of Conservative MPs are landlords, 11 per cent of Labour MPs, nine per cent of SNP members, 25 per cent of Lib Dems, and 10 per cent of the Democratic Unionists.

In the last parliament, many MPs who let out property were criticised for contributing to votes seen as supporting landlords.

Most famously, says FactCheck, 72 landlord MPs were among those who voted down requirements on landlords to ensure that homes are “fit for human habitation” in a Private Member’s Bill last year.