Royal Bank of Scotland, parent of wealth management houses Coutts and Adam & Co, said the bank will re-domcile its holding company in England if Scottish voters say “yes” to independence.

Royal Bank of Scotland, parent of wealth management houses Coutts and Adam & Co, issued arguably the most dramatic intervention yet by a business about the Scottish referendum debate, saying the bank will re-domicile its holding company in England if Scottish voters say “yes” to independence.

While the latest polls are said to show a small lead for those likely to vote "no" to independence, some polls that have suggested the race is headed for a close finish have prompted fears about how large businesses, facing the potential disruption, will react.

Already, firms such as Edinburgh-headquartered Standard Life, the financial services and investment firm (parent of Standard Life Wealth), have warned they may quit Scotland as a headquarters if there is a vote for independence. Lloyds Banking Group - also part-owned by the UK taxpayer - has issued a similar warning to that of RBS. There are fears that an independent Scotland will be unable, shorn of financial support from the rest of the UK, to stand behind large financial institutions. RBS is majority-owned by the UK taxpayer. The combined balance sheets of RBS and Lloyds Banking Group, for example, are about 12 times the size of Scotland’s GDP.

“The Royal Bank of Scotland Group confirms that, as set out in the risk disclosures in RBS's Annual Report, there are a number of material uncertainties arising from the Scottish referendum vote which could have a bearing on the bank's credit ratings, and the fiscal, monetary, legal and regulatory landscape to which it is subject,” the bank said in a statement to the London Stock Exchange.

“For this reason, RBS has undertaken contingency planning for the possible business implications of a 'Yes' vote. RBS believes that this is the responsible and prudent thing to do and something that its customers, staff and shareholders would expect it to do,” it continued.

”RBS believes that it would be necessary to re-domicile the Bank's holding company and its primary rated operating entity (The Royal Bank of Scotland plc) to England. In the event of a 'Yes' vote, the decision to re-domicile should have no impact on everyday banking services used by our customers throughout the British Isles. However, RBS believes that it would be the most effective way to provide clarity to all our stakeholders and mitigate the risks previously identified in our Annual Report,” it said.

”The vote on independence is a matter for the Scottish people. Scotland has been RBS's home since 1727. RBS intends to retain a significant level of its operations and employment in Scotland to support its customers there and the activities of the whole bank,” it added.