Simplex was a motorcycle produced from 1906 to 1908.
Hobday Bros. (Stand 189).
The Simplex motor bicycle is a machine of extra long wheelbase, fitted with a 3½ h.p. Fafnir engine governed on the inlet valve. Simplex spring forks are fitted, and a rim brake is fitted to the front extension of the fork. The magneto is situated in front of the engine and is gear driven. Another machine shown on the same stand is a twin-cylinder Antoine, which has not been altered since previously described in these columns.
Previously Hobday had presented a water-cooled Bruneau machine at the 1905 Stanley Show
Source: Graces Guide
N.B. Several firms used variations of the Simplex brand.