The by-election was triggered by the resignation of the sitting Conservative Member of Parliament (MP) David Cameron, the former prime minister, on 12 September 2016.

Following the Leave result in the referendum on the United Kingdom's membership of the European Union that Cameron had campaigned against, he resigned as Prime Minister and leader of the Conservative Party, being replaced by Theresa May.

[8] The Liberal Democrats selected Liz Leffman, a West Oxfordshire District Councillor (for Charlbury and Finstock) and local businesswoman, as the party's candidate.

[10] He served in the army in Oxfordshire's local Regiment, The Royal Green Jackets, before becoming Head Porter at Oriel College, Oxford,[11] and stood in Banbury in 2015, coming third.

[13] The National Health Action Party (NHA) selected Dr Helen Salisbury, a GP and lecturer at Oxford University Medical School.