Scottish independence would lead to a sharp fall in exports to England and hit household incomes, with the SNP’s planned separate currency worth about 20 per cent less than the pound, a leading economist has suggested.

Tony Mackay, who advises the World Bank, the Asian Development Bank and the European Commission, said “there can be no doubt that an independent Scotland could be economically viable”, but voters deserve objective analysis about its implications.

In a paper for The Sunday Times, Mackay, who advised the government of Bosnia-Herzegovina after its independence from Yugoslavia, said: “The bottom line is that average incomes in Scotland would be lower. Many people would be unaffected but those working in export industries and the public sector would be. Foreign holidays, including…