THE Yes campaign has come under a concerted attack from the UK's political leaders and big business as a new poll showed it six points behind the No camp and reports claimed Royal Bank of Scotland will today announce plans to register its headquarters in London in the event of a Yes vote.

Lloyds Banking Group, which owns Bank of Scotland and Scottish Widows, last night confirmed it would register its head office in England.

The developments came on the day Prime Minister David Cameron, his deputy Nick Clegg and Labour leader Ed Miliband travelled to Scotland to warn of the dangers of the UK breaking up.

Today's Survation poll for the Daily Record puts the Yes camp six points behind. Support for independence is at 47 per cent, against 53 per cent for a No vote, discounting undecided voters, with the results unchanged from its previous survey published at the end of last month.

Last night treasury sources said the Edinburgh-based, part-taxpayer-owned RBS had "been in touch" about "similar plans" to Lloyds which confirmed it would also consider switching its registered office to the UK capital.

Earlier, Mr Salmond dismissed as "nonsense" and "scaremongering" contingency plans by Edinburgh-based Standard Life to move its pensions arm and other operations south of the Border in the event of a Yes vote.

BP insisted the future of North Sea production was best served by Scotland remaining in the UK and billionaire financier George Soros said monetary union with the UK was potentially dangerous. Mark Carney, the Governor of the Bank of England, warned an independent Scotland would have to raise billions of pounds in currency reserves.

The future of the NHS, which has emerged as a key battleground in the campaign, is thrust centre-stage today with revelations that emergency plans have been drawn up to divert patients from short-staffed hospitals. Official NHS Lanarkshire papers detail plans to shift patients from A&E departments because of "fragile" staffing levels.

Mr Cameron, Mr Miliband and Mr Clegg yesterday abandoned Westminster and Prime Minister's Questions to make emotional pleas for Scotland to stay in the UK. In Edinburgh, Mr Cameron stressed the historic poll was unlike a General Election and, acknowledging his party's unpopularity in Scotland, said the vote should not be about kicking "the effing Tories".

Mr Miliband, addressing supporters in Cumbernauld, appealed to Scots' sense of solidarity with the rest of the UK. In Selkirk, Mr Clegg said the United Kingdom had done "extraordinary things together" including competing at the Olympics, defeating facism and creating the NHS.

Meanwhile, Better Together strategists were hopeful the latest poll, conducted before the Westminster leaders announced their visits, represented a hardening of the No vote after YouGov gave a two-point lead for the Yes campaign at the weekend.

Ladbrokes shortened the odds on a No vote from 4/11 to 4/9. The odds for a Yes vote lengthened from 2/1 to 7/4.

At Westminster, Mr Carney said an independent Scotland would need to raise billions in currency exchange reserves if it kept the pound without a formal deal with the UK.

Glasgow University economist Professor Ronald MacDonald said ­keeping the pound informally would lead to at least £40 billion of cuts or tax rises as reserves were built up.

The Financial Times today comes out in favour of a No vote. It says the case for the Union is overwhelming, and "the path of separation is a fool's errand".

Meanwhile, UK Government whips are contacting MPs to find out their whereabouts after next Thursday in case a Yes vote causes an emergency recall of Parliament.