Speaking at a referendum debate organised by the Federation of Small Businesses (FSB) on Wednesday, Labour's finance spokesman Iain Gray said: ‘If you deliberately set your corporation tax, not at what you think is right, but less than the country next door to you, what you're doing is, you're trying to create yourself as a tax haven.’

Citing the example of Ireland, which also introduced a lower level of corporation tax, Gray said that what would happen ‘of course’ is that multinational companies like Google and Microsoft would set up shell companies to use as a conduit in order to pay less tax.

His opponent at the debate, Scottish finance secretary John Swinney, denied this would be the case and pledged that multinationals would pay their fair share in the event of a yes vote next month.