David Cameron is already coining it in post Downing Street after lining up lucrative speech to a US private equity firm

DAVID Cameron is already coining it in post Downing Street as the ex-Prime Minister is set to give a speech to a US private equity firm.

He will address advisers and investors in US company, Bain Capital, which bought a unit of the NHS during his premiership in 2012.

It came as Samantha Cameron got her post-Number 10 fashion career underway as the former PM’s wife registered a company, Samantha Cameron Studio Ltd, in a move that appears to confirm rumours she is launching a own clothing range.

Bain Capital was co-founded by ex-Republican presidential candidate Mitt Romney - but he has not been involved with the company for 17 years.

It is unclear how much he is going to be paid for the speaking engagement.

Pal George Osborne charges £75,000 to give after dinner speeches, as revealed by The Sun earlier this month, after signing up with a US company that has ex-PMs Gordon Brown and Tony Blair on its books.

But as Mr Cameron has stepped down as an MP, he does not have to publicly disclose earnings.

Although this engagement could suggest he intends to follow them in cashing in on the lucrative international speaking circuit.

He has given little indication of life after Downing Street plans, other than chairing a panel of patrons on the expanded National Citizen Service, a summer camp initiative that was part of his “Big Society”.

Tom Kenyon-Slaney, who set up the London Speaker Bureau, one of the biggest speaker agencies, said he had asked Cameron to sign up with his company, but understood that the former prime minister had chosen the Washington Speakers Bureau instead.

Bain Capital declined to comment.