David Cameron heaped praise on the NHS chairman as he sought to lobby the health service on behalf of Lex Greensill, The Telegraph can disclose.

       In an email dated July 23, 2019 and obtained under the Freedom of Information Act, Mr Cameron asked whether he could introduce Lord Prior, his former health minister, to Mr Greensill, to whom the former Prime Minister was a paid adviser.

       It has previously emerged that Lord Prior arranged for Mr Greensill to see Julian Kelly, NHS England's chief financial officer, in a July 2019 meeting attended by Sir Simon Stevens, the NHS chief executive.

       The email to Lord Prior was not among the 68 messages Mr Cameron later sent to ministers and officials, which were published in May by a committee of MPs.

       In the email to Lord Prior, he said: "I'm so glad that you are battling for NHS improvement; it is reassuring to know that there is such an experienced and safe pair of hands at the helm."

       He appeared to be paving the way for Mr Greensill to encourage the NHS to use Greensill's early payments scheme for health workers.

       Lord Prior responded in less than four hours, stating that he was already due to see representatives of Greensill the following day, and adding: "Hope we can make some progress."

       Mr Cameron's email praised Mr Greensill's "impressive company", which was "rapidly turning into one of the UK's best FinTech success stories."He said he was "pleased to hear" that Lord Prior was already "in touch with … Greensill looking into possibilities for how they can further support the NHS".

       He added that he "would love to see you for a catch-up at some point" and introduce the peer to Mr Greensill "himself". NHS England has said that it did not take the proposals forward.

       A spokesman for Mr Cameron said: "David Cameron and David Prior have known each other for many years. The email and language used is perfectly consistent with that – it is preposterous to suggest anything else.

       "[He] sincerely believed there would be considerable benefits to the NHS and NHS workers. He acted in good faith at all times, and two reports have confirmed that he broke no rules."