Hair did not vote in the 2016 UK EU Membership referendum. In September 2017, she commented that she chose not to vote at the time as she could not decide on whether to support the UK leaving or remaining within the EU as she felt that there were strong arguments on both sides. She voted for then Prime Minister Theresa May's Brexit withdrawal agreement in early 2019. In the indicative votes on 27 March, Hair voted against a referendum on a withdrawal agreement, against a customs union with the EU, and against single market membership.