Olney joined the Liberal Democrats in July 2015, soon after the general election, in realisation that she was a liberal dissatisfied with the direction of the United Kingdom. On 25 October 2016, Conservative MP Zac Goldsmith announced his resignation from the House of Commons over his objection to his party's support for a third runway at Heathrow Airport, triggering a by-election in his seat of Richmond Park. Goldsmith stood in the by-election as an independent candidate although he remained a Conservative party member with the support of Nigel Farage's UKIP, who along with the Conservative party, did not put forward a candidate. On 30 October 2016, Olney was announced as the Liberal Democrats' candidate for the by-election. On 1 December 2016, after overturning a majority of over 23,000 votes, Olney was elected as the Member of Parliament for Richmond Park. She received 20,510 votes, giving her a majority of 1,872 votes. She was the only female Liberal Democrat MP in the 2015–2017 parliament. Shortly after her election, Olney ended a radio interview in which she was pressed on her support for a second Brexit referendum. Supporting a second referendum became official Liberal Democrat policy shortly after. In the run-up to the 2017 General Election, Olney was recorded urging Liberal Democrats to vote for Labour MPs in seats where Labour candidates stood a better chance of defeating Conservatives than the Liberal Democrat candidates. Olney referred to the Liberal Democrat candidate for Ealing Central and Acton as a "paper candidate" and voiced her support for the Labour Party incumbent Rupa Huq. It was reported by the Evening Standard in April 2018 that Olney had been interviewed under caution by the police for allegedly breaking official spending limits in the Richmond Park by-election. The Crown Prosecution Service ruled that there was no evidence and closed the case. In the 2017 general election, Olney narrowly lost her seat to Goldsmith, who stood as the Conservative candidate, polling 45.07% of the vote to Goldsmith's 45.14%, giving Goldsmith a majority of 45. On 9 September 2017 it was announced that she would be taking up the post of chief of staff for Liberal Democrat leaderVince Cable. In 2019, she was officially confirmed as the Liberal Democrat candidate for Richmond Park at the next general election. She won the election.
Views
On the topic of Brexit, Olney voted against the triggering of Article 50, as she had indicated during the by-election campaign that she would do. She believes another referendum should be held once the exact terms of Britain's exit from the EU have been announced. Olney opposes the building of a third runway at Heathrow Airport.
Personal life
Olney has two children with her husband Ben, a town planner.