Thomas Tompion was born around 1639 and was baptized on 25 July 1639 in Northill, Bedfordshire, England. He was the eldest son of a blacksmith, also named Thomas Tompion, and probably worked as a blacksmith until 1664 when he became an apprentice of a London clockmaker. Very little of his earlier years is known. The first reference to Tompion in London is recorded around the end of 1670 in Water Lane (now Whitefriars Street) off Fleet Street.
Tompion was an early member of the Clockmakers' Company of London - he joined 1671 and became a master in 1704. He was also one of the few watchmakers to become a member of the Royal Society. He joined in partnership with Edward Banger in 1701 until about 1707 or 1708.
When the Royal Observatory was established in 1676, King Charles II selected Tompion to create two clocks based on an escapement designed by Richard Towneley, that would be wound only once a year. They proved to be very accurate and were instrumental in the accurate calculations for astronomers.
Due to his relationship with the scientist Robert Hooke he made some of the first watches with balance springs. These were much more accurate than earlier watches. He invented the first widely used balance spring regulator, used in pocketwatches until the late 1800s. He also invented the cylinder escapement that allowed him to create flat watches. He also worked on the spring escapement.
As England's most prominent watchmaker, Tompion built about 5,500 watches and 650 clocks during his career. Tompion's clocks are known for their ingenuity of design and robust construction. His three-train grande sonnerie bracket clocks are masterpieces. Another of his innovations was to create a numbering system for his spring and long-case clocks which is thought to be the first time that a serial numbering system was applied to manufactured goods.
In 1711 Tompion joined in partnership with George Graham, who later developed the spring escapement further after Tompion's death. He also continued Tompion's scheme to number his watches in three series: plain, repeating and special.