The SNP leader was questioned closely by Andrew Neil on 25 November about what currency and monetary authority Scotland would have if it achieved independence.
At the launch of the Scottish Conservative manifesto the following morning, Boris Johnson claimed that in the course of the interview Nicola Sturgeon had said SNP policy was “to join the Euro.”
Andrew Neil asked which currency Scotland would use if it became independent and which monetary authority it would report to. Nicola Sturgeon responded that “the pound is Scotland’s currency right now. The proposition is that until the conditions were right to establish our own currency, which we said would be our objective, we would use the pound.”
Neil pressed her about how Scotland, as a member of the EU, could use a currency which was regulated by a monetary authority which was not part of the EU. His implication was that Scotland would have to have an independent currency before joining the EU. She responded that "it is not true to say Scotland would have to have established an independent currency before joining the EU."
A full analysis of this comment is provided by BBC Reality Check
And on monetary union with the UK, she said “there is still an argument for monetary union. What was demonstrated in 2014 was that Westminster could operate a veto on that, so we have set out very clearly the conditions for moving to a separate currency and the preparations that would be required to be made."
This is a complex issue. New member states do have to commit in principle to joining the Euro once they have met certain economic criteria. However, the EU is unlikely to set specific deadlines for this to happen or force a country to join. At present seven existing member are neither in the Euro, nor have opt-outs. Moreover, SNP policy is not to join the Eurozone, but instead use sterling until an independent currency can be established.
Boris Johnson could argue that Eurozone membership is implicit as a long-term consequence of joining the EU. But Nicola Sturgeon did not say the words he attributed to her, indeed, she stated something completely different. Johnson's claim that SNP policy is to join the Euro was a gross misrepresentation. Nicola Sturgeon responded to the prime minister’s remarks with "Boris Johnson is lying." She was entitled to say so.