BANNING EU migrants for four years from receiving in-work benefits remains the “best way forward” to reduce the pull-factor to Britain, David Mundell has insisted as the Prime Minister appears to have shifted his emphasis towards the ends and away from the means of achieving reform.

On Thursday evening, David Cameron faces a challenging discussion over dinner with his EU counterparts, many of whom are steadfastly opposed to his key demand of a four-year benefits ban.

While the Scottish Secretary and No 10 insisted that this option remained on the table, it seems increasingly clear that the PM might have to look to over alternative political dishes to satisfy his appetite for reform.

UK Government sources have suggested officials are being told to find an option that meets British demands while also being acceptable to all other member states. One said: “What matters most is to fix the problems, not the precise form of the arrangements."

He added: “On welfare, the Prime Minister will aim to unlock the political will necessary to find a solution, effectively giving the green light to officials to work up a solution that would both deliver on his objective of better controlling migration from the EU while also being acceptable to all."

Other options could be: to allow the UK to operate an “emergency brake” if net migration – now running at a record high of more than 330,000 a year – became so great as to put unbearable pressure on public services or to focus on limiting out-of-work benefits.

Such changes would not conflict with the principle of the free movement of labour; nor would they require treaty change.

Downing Street has already expressed encouragement that the export of child benefit to migrants’ children abroad is something that EU partners could agree to ban.

Last week on a visit to Poland, Mr Cameron once again met fulsome opposition to his plan to curb in-work migrant benefits from his Polish counterpart; east and central European partners are said to be particularly hostile to the PM’s reform plan.

Eurosceptic Owen Paterson, the former environment secretary, appeared unimpressed by his party leader’s efforts, saying: “He is like someone in a little dinghy, bumping along, being towed along by the enormous great Channel ferry.”

Hilary Benn, the shadow foreign secretary, noted: "The Prime Minister has been undone by his own failure to build alliances and goodwill through patient diplomacy.”

Arguing how it was never a good idea to reduce the future of UK co-operation to a single issue, he added: "The PM now needs to get on and make the broader case for remaining part of Europe as Labour has been doing."

But Mr Mundell said there had been no change in the UK Government’s position; the four-year ban was the “best way forward and it’s a position we will continue to argue for”.

He added: “It’s clearly a negotiation though and if others come forward with other proposals, then you have to look at what is being put forward; that’s where we are.”

The Scottish secretary also claimed Nicola Sturgeon, the First Minister, had “recently backed away” from her insistence that a UK vote to leave the EU while Scotland voted to stay would be an automatic trigger for a second independence referendum.

He said: “When we had a referendum in Scotland, we didn’t say that if specific parts of Scotland voted to remain in the United Kingdom then those parts of Scotland wouldn’t become independent. This is a UK-wide poll in relation to the UK as the member state remaining in the EU.”

Mr Mundell added: “What I would say to the SNP is: if they believe that Scotland is better off in the EU, the UK is better off in the EU, come out and argue that case; don’t constantly put everything through the prism of your sole objective of independence.”