Pioneering clockmaker John Harrison died 250 years ago this month, on 24 March 1776. The self-taught joiner took on the establishment of the day and, thanks to his determination and extraordinary insight, succeeded in solving one of the greatest scientific problems of the age: how to find longitude at sea.

John Harrison and the Quest for Longitude is the story of this now famous watch- and clockmaker and the intricate timepieces he created, featuring beautiful photography and diagrams showing their workings. The marine timekeepers are true treasures in the collections of Royal Museums Greenwich and perennial favourites with visitors to the Observatory.