David Cameron has suggested he would like to strap some of his former Cabinet colleagues on a raft and send them down a "very, very dangerous river".

The former prime minister warned that the Conservatives risked "slipping backwards" by moving away from the liberal agenda he championed as leader from 2005-16.

And he suggested that the administration that succeeded his last year needed to do more to present an "inspiring vision" to counter the appeal of Labour's Jeremy Corbyn.

Speaking to the Evening Standard after chairing a board meeting of patrons of the National Citizen Service (NCS) scheme, which he founded, Mr Cameron said: "It is very important that the Conservative Party doesn't slip backwards.

"The Conservative Party only succeeds if it is a party of the future.

"Modernisation isn't an event. It is a process. A political party should be asking itself all the time, 'Am I properly in touch with and reflecting the society and the country?'.

"I want us to go on being the open, liberal, tolerant party that we became post-2005 because I think that was part of our success."

Asked whether any of his former Cabinet colleagues could benefit from the kind of outward-bound courses which NCS provides, Mr Cameron said: "If it involved crossing a very, very dangerous river on a raft, I can think of a few I'd want to strap together."

Mr Cameron said that Tories needed to push their idealistic vision to counter Mr Corbyn's drive for younger voters.

"We on the centre-Right side of the argument have to have just as inspiring a vision - a more inspiring vision - of how you build not just a strong economy but a strong society and a better life," he said.

A lot of young Corbyn backers had "forgotten just how dangerous this full-on programme of nationalisation, state control and rampantly high taxes can be", he said.

Mr Cameron said he was halfway through writing his memoirs and was enjoying the process, even though it was "hard work".

He said he hoped they would be "a rip-roaring read".