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The 'British Tabulating Machine Company' (BTM) was a firm which manufactured and sold Hollerith punched-card machines and other data-processing equipment. During World War II, BTM constructed a number of "bombes", machines used at Bletchley Park to break the German Enigma machine ciphers.
The company was formed in 1902 as 'The Tabulator Limited', after Robert Porter obtained the rights to sell Herman Hollerith's patented punched card machines from the US Tabulating Machine Company (later to become (IBM). By 1909, the company had been renamed the "British Tabulating Machine Company Limited". In 1920, the company moved from London to Letchworth, Hertfordshire; it was also at this point that it started manufacturing its own machines, rather than simply reselling Hollerith equipment.
Annual revenues were £6K in 1915, £122K in 1925, and £170K in 1937. In 1916 there were 45 staff; this increased to 132 in 1922, 326 in 1929 and 1225 in 1939.
In return for the exclusive right to market Hollerith equipment in Britain and the Empire (excluding Canada), BTM paid 25% of its revenues to the American company by way of royalties. This became an ever-increasing burden as the years progressed; BTM attempted to renegotiate the agreement on several occasions, but it was only finally terminated in 1948.
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