Plans for Britain to move on to "perpetual summer time" have been given tentative backing by the Government.
Under the proposal, Greenwich Mean Time would be effectively abolished and clocks in the UK would go forward by one hour all year round. Ministers are considering supporting a Private Member's Bill which would pave the way for moving the country in line with Central European Time (CET) for a trial period of three years.
But the plan could still be scuppered as it would get the go-ahead only if Scotland and the other devolved administrations agree to go along with it. Last night, the SNP signalled that they would oppose the move.
Moving to CET would mean lighter winter evenings, which supporters claim would cut road deaths, boost tourism and reduce energy use. But northern parts of England and Scotland would face winter mornings which would not be light until 9am. Critics claim this would increase the dangers for many workers, particularly farmers, as well as families on the school run.
During during a visit to Australia, Mr Cameron said: "I've always been interested in this debate as someone who likes playing sport and all the rest of it. But I've always felt you could only do this as a United Kingdom and there have always been very strong arguments made in Scotland.
"Discussions are under way across Whitehall and with the devolved authorities but that's the key; you can only do this if there is real national consensus and pressure between all the nations of our United Kingdom."
The Daylight Saving Bill, tabled by Rebecca Harris, Conservative MP for Castle Point in Essex, calls for a review of the potential costs and benefits of a move to CET and would need further legislation before any trial was launched.
The Bill will still need the backing of MPs and peers by April next year to go ahead. Ms Harris said: "I am delighted the Government is minded to give its support. There are so many conflicting arguments on both sides of the daylight-saving lobby. I believe we need a comprehensive and objective assessment of them."
But SNP MP Angus MacNeil dismissed the plans, arguing the move would hit everyone living north of Manchester. "It is no secret that Tories in the South want to leave Scotland in darkness, but fixing the clocks to British summertime would mean that dawn wouldn't break in Scotland until nearly 9am," he said.
Clocks go back an hour at 2am tomorrow when British Summer Time ends.