John Arnold was born in Cornwall in 1736 as the son of a watchmaker. He left England for the Netherlands at the age of 19 and returned to London two years later speaking excellent German. This stood him in good stead at the court of George III, from the house of Hanover, to whom Arnold presented the smallest repeating watch ever made.
He was one of the most inventive watchmakers of his day and held patents for a detent escapement, bimetallic balance and helical balance spring. Arnold also played a central role in the significant events of his age, such as the competition to determine longitude at sea, and won several grants and awards offered by the British Parliament.