The SNP leader mixed up Sussex and Wessex when he attempted to welcome the new royal baby during PMQs.
Ian Blackford went on to ask the prime minister about her cross-party Brexit talks, and told her Scotland did not want “a Labour-Tory stitch up”.
Theresa May said she had talked to Mr Blackford, and to First Minister Nicola Sturgeon, about Brexit, and she was “absolutely of the view” that her job was to deliver what the UK voted for in the 2016 referendum.