[9] Following her marriage to Colonel Sam Janson, a director of the Spyker car company, on 17 February 1920 in Brompton, Gwenda became interested in motor-cycle racing, competing in events at Brooklands.

[8] In 1930, Gwenda turned in a speed of 113 mph (182 km/h) in a race-tuned British 3-wheeler created by Morgan Super Sports.

[11] Douglas Hawkes was a director of the Derby engine and car company and was able to source a Miller Special from the United States.

In the period between 1930 and 1933, in the Miller-derived car specially prepared by Derby and designated as a Derby-Miller, Gwenda broke the one-mile speed record several times at Montlhéry.

[8] Gwenda also competed on two occasions, with little success, in the 24 Hours of Le Mans event, at the wheel of a Derby car using a Maserati engine.