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The Whitlock Company, based in London, England, started as a carriage builder in 1778, moved into the car industry in 1903. A company with the Whitlock name finally closed in 1991.
Joseph Whitlock had set up his company making coaches and carriages in Holland Park, London in 1778. They must have been successful as by the start of the twentieth century they described themselves as "Coachbuilders to the Royal Family".
1902 the company was named Henry Whitlock and Co
1903 Moved into the car business when they started to sell the Whitlock Century. They had not built this themselves however, it was a re-badged car from Century, a manufacturer in Willesden, London, but they may well have built its body.
1904 the range was expanded with cars from the French Aster makers again probably with Whitlock's own coachwork.
A separate company was formed in 1905 called The Whitlock Automobile Company who continued to market the Whitlock-Aster cars which were well received but cannot have been a commercial success as the company closed in 1906.
1905 September. Details of the Whitlock-Aster T.T. car.
1906. Whitlock-Aster. Produced 10-12 h.p., 12-14h.p. twin cylinder shaft drive and 12 h.p., 18 h.p. and 24 h.p. models but listed as of French manufacture. 
One Whitlock car is known to survive.
Meanwhile, another coachbuilder had been operating in Liverpool founded in 1870 by Joseph Alfred Lawton, called J. A. Lawton and Co. They also turned to car-body making and in the early 1900s opened a London works run by William Lawton Goodman, Jo Lawton's nephew. Jo died in 1913 and left the company in his will to his brother leaving William with nothing so he started a new company Lawton-Goodman and took over the defunct name of Whitlock and moved to new premises in Slade Works, Cricklewood, North London. Two new models were announced, initially called Lawtons but rapidly changing to Whitlock but before production could be established war broke out. During the war years the company concentrated on building ambulances, both on their own and on other makers' chassis, and fuselages for De Havilland DH4 aircraft.
1913-1917 For a list of the models and prices see the 1917 Red Book
In 1924 a new range of cars was announced still using bought in mechanical components. The smallest was the 11, 12 or 12/35 built until 1925 and using a Coventry Climax(or Coventry Simplex) engine of 1368 cc or an Anzani engine of 1,496 cc. Larger was the 14, also called the 16/50, with a six cylinder 1755 cc or 1991 cc Coventry Climax built from 1924 to 1926 and bigger still the 20/70 with 6 cylinder 2,973 cc Meadows engine made from 1926 to 1930. The latter car had a radiator very reminiscent of their near neighbours Bentley. William Lawton-Goodman died in 1932 but his sons carried on the business turning to commercial vehicle bodies but continuing some car body work.
During the Second World War they returned again to making ambulances. With peace in 1945 they seem to have concentrated on making mobile shops and ice cream vans continuing to the early 1980s, after which they concentrated on repairs. In 1991 the lease on Slade Works ran out and the company closed.