Cooke, Troughton & Simms was a British instrument-making firm formed in York in 1922 by the merger of T. Cooke & Sons and Troughton & Simms. Origins Thomas Cooke set up a business in York in 1837 making astronomical telescopes. One early notable instrument was a 4.5 inch equatorial refractor which would have been exceptional at the time. In 1851 Cooke built a 7.25 inch equatorial telescope. Cooke made the optical elements himself for both these instruments. Thomas Cooke built a reputation for high quality optics and, as well as smaller instruments, supplied large instruments to observatories around the world. From the outset in 1826 and earlier Troughton and Simms of London excelled in the high precision work of dividing circles and so provided many observatories with large transit instruments and supplied national surveys such as the Ordnance Survey, with large transit theodolites. Merger In 1922 with business in a depressed state Cooke and Troughton & Simms merged with head offices at York. However foreign competition was strong. In particular the Swiss firm of Wild was making theodolites which were lighter, smaller and more accurate than CTS products. Vickers ownership In 1924 the company became a wholly owned subsidiary of Vickers. In 1926 a meeting was held in Tavistock, Devon with representatives from the Admiralty, the War Office and the Ordnance Survey and Cooke, Troughton & Simms, E. R. Watts and C. F. Casella & Co. On Dartmoor a comparison was made between the products of UK companies and their European competition, especially the Wild T2 theodolite which pioneered enclosed glass circles rather than exposed brass ones. Results were depressing for the British firms. One result of this event was the Vickers CTS "Tavistock" theodolite which appeared in 1930. The unusual circle reading eyepieces which projected out from each side arose from a wish to avoid infringing the Wild patents. Work began in the autumn of 1931 on the Geodetic Tavistock. where the increased accuracy made it suitable for primary surveys of Canada, Australia, New Zealand, the East African Arc and the re-triangulation of Great Britain. In response to user requests a second, lighter version the Geodetic Tavistock appeared in 1937 By 1932 the depressed state of trade had reached a point where the York factory was working at only 40% capacity but was kept going making optical components for Vickers Armstrong and also building the Vickers Projection Microscope. By