Cecil Kimber ultimately won approval to build a true sports car. The first one was built specifically for entry into the Lands End Rally in early 1925, in which the car took top honors. It was initially painted gray and had the MG octagon symbol painted on the side. In retrospect Cecil Kimber himself dubbed this one the first MG he ever built. But still there was no M.G. Car Company.

Notice the MG octagon on the side in 1925.
Photo from MG Enthusiast magazine, August 1990

Click for magazine articles:
Number One - Autocar, March 2, 1934 (0.7-MB pdf)
Land's End Pilgrimage - T&CC, March 1975 (1.1-MB pdf)