Steve Double, Conservative MP for St Austell and Newquay has said he will vote against the government.
"There's all sorts of rumours going around about may or may not happen.
"We'll wait and see what the Government actually come forward with - something I would be interested in is if the Government actually want to make the case for this then lets run a trial, lets put a pilot scheme out there and see what actually happens."
He was speaking as the House of Commons waits to hear how the Scottish National Party votes. It has declared it will oppose relaxing Sunday trading laws less than 24 hours before a crucial vote on the issue.
The Government is facing the prospect of a damaging Commons defeat on Wednesday over plans to relax the laws in England and Wales, after the SNP said it would vote with Tory rebels and Labour to block the measure.
This has angered ministers as the SNP previously said it would abstain from the vote; one Government source has called their action as "disappointing and hypocritical".
Speaking to Premier earlier in the week Jonathan Ashcroft, from the Keep Sunday Special campaign, who is also against the relaxing of trading laws, told Premier Scotland would miss out with the changes.
He said: "Scottish shop workers are likely to lose premium payments, and that means that some Scottish shop workers could lose as much as £1,500 a year.
"Now, nothing that the government has done has changed that fact.
"An analysis by Oxford Economics suggested there would be a net loss of jobs in the retail sector of 3000 jobs, which is the consequence of driving trade from some of the small convenience stores to the large supermarkets."
The Church has consistently said that the move would damage family and community life.
At present smaller stores can open for more than six hours on a Sunday but larger supermarkets cannot.
Up to 30 Tory MPs are reportedly planning to defy the whips and vote against the plan - and another 20 say they are ready to abstain.
The SNP had previously indicated that they would not try to defeat the measure, following assurances UK employment laws would be amended to protect workers from being required to work on Sunday against their wishes.
However after a meeting with the shopworker's union Usdaw, they became concerned that Scottish worker's premium pay rates for working Sundays could be in jeopardy if Sunday trading laws were liberalised below the border.
The SNP's Stewart Hosie said: "We've listened to arguments on both sides and we are convinced that should this become a UK-wide system, then the premium pay that does exist for many workers would be eroded.
"In all conscience, we simply couldn't support that."
A Government source said it was "extraordinary" that a party which campaigned for devolution from Whitehall was now opposing passing more powers to local councils.
It also says the move would boost the economy, and gives shoppers more choice.
The Chancellor George Osborne also said extending Sunday trading laws does not go against Britain's Christian heritage, using countries like the US - where they're relaxed - as an example.
Steve Double, Conservative MP for St Austell and Newquay has told Premier that he will be voting against David Cameron.
He said he did not agree with the argument of economic benefit for the country.
Listen to Premier's Hannah Tooley speaking to Steve Double here:
