Simon Bull joined Christie's in 1969 and established their specialized department of Clocks, Watches and Scientific Instruments. He left them in 1976 to become a director of a company specializing in Antiquarian Horology, later becoming an independent dealer and consultant. In 1990, he joined the Swiss-based European auctioneers Antiquorum, for whom he still works as an independent consultant. He contributes to art and antiques magazines and writes catalogues for various foreign museums. He also works as an independent advisor for museums and is currently a director of T.H.A.—a Swiss company specializing in the design and manufacture of clocks and watches for several of the world's best-known luxury brands. He is president of L. Levoy Watches, the oldest surviving watch-making firm in France. In his spare time he runs vintage cars and collects historic formula one racing cars.