Sir Andrew Longmore was educated at Winchester College and at Lincoln College, Oxford. He was called to the Bar by Middle Temple in 1966, and became a tenant at 7 King's Bench Walk. He practised commercial law, in particular insurance and reinsurance, and shipping and international trade. He was appointed Queen's Counsel in 1983 and became a Recorder in 1992. In 1993, he was appointed a Judge of the Queen's Bench Division and nominated to sit in the Commercial Court. He became a Lord Justice of Appeal in 2001. He retired from the Bench in 2019.

Sir Andrew is a former editor of 'MacGillivary On Insurance Law'. He enjoys fell-walking.