Sheffield-Simplex

thumb|1913 LA7b 30hp open tourer Sheffield-Simplex was a British car and motorcycle manufacturer operating from 1907 to 1920 based in Sheffield, Yorkshire, and Kingston upon Thames, Surrey.

The company received financial backing from aristocrat and coal magnate Earl Fitzwilliam. The first few cars were made by Peter Brotherhood and were a continuation of the Brotherhood-Crocker cars made in London in which Earl Fitzwilliam had been an investor. Stanley Brotherhood sold the London site in 1905 and moved his Peter Brotherhood business to Peterborough, near Fitzwilliam's second seat at Milton Park. He could not get permission to build a car factory in Peterborough so the Earl suggested a move to Sheffield where Stanley Brotherhood built a new factory in Tinsley a few miles south of Wentworth-Woodhouse, the Fitzwilliam family seat.