Given that it is the political union that will end if Scots vote for independence, this will have little if any impact on the current single market of 60 million people.
However, Scotland does not solely operate within a single market of 60 million but within a single market of 500 million, more than six times this size, comprising 28 European Union member states.
That relationship is set to be put to the test with the proposed Conservative In-Out referendum in 2017. Should Scotland vote No to independence, that single market of 500 million would be closed off to Scotland through a vote to leave the EU, even if Scotland votes against this.
The choice on 18 September is simple: a Scotland open for business through independence or cut off from many of our key trading partners as the UK withdraws from the EU.