As the Opposition Leader, Malcolm Turnbull, arrived home last night after a week abroad, he faced reports the majority of his back bench opposed his intention to negotiate a deal with the Government, and assertions from within that an emissions trading scheme was never Coalition policy.

The Coalition legislated for such a scheme in its final months in power and took it as policy to the last election. The scheme was designed by a team led the former chief public servant Peter Shergold.

But yesterday climate change rebels Cory Bernardi and Ron Boswell articulated the growing view internally that the policy, devised by John Howard and Mr Turnbull when he was environment minister, was never run past the party room and was therefore questionable.

"I have no recollection of it. I understand there was an agreement between the prime minister and Mr Turnbull," Senator Bernardi said. "It was announced unilaterally just prior to the election and, of course, we did what we thought was in the best interests of the party."

To dispute this, Mr Macfarlane emailed every backbencher with a copy of the policy the Coalition took to the last election as well as the speech Mr Turnbull gave to Parliament in 2007 when he introduced the legislation.

"Everyone was aware of Shergold; everyone knew what it said," he told the Sydney Morning Herald.

The frontbencher Helen Coonan said she recalled the Shergold scheme going to the party room, but another former cabinet minister said it was presented as a fait accompli.

There had been one cabinet discussion about the scheme. Mr Howard had wanted it kept secret so it would not spoil his announcing it at the Liberal Party federal council meeting in July 2007.

"There was never a detailed internal discussion," the former minister said.