The real facts as per Horler in OS&M are:
Bugeyes;
Speedo, SN 6155/10 or SN 6155/11, RED ignition warning light
Rev counter, RN 2351/02, RED high beam warning light
These 'warning' lights had small plastic flat disc's
Sprite Mk-II & Midget Mk-I's had;
Speedo, SN 6126/00, BLUE main beam warning light
Rev counter, RN 2313/00, RED ignition warning light
These 'warning' lights had small "jeweled" plastic lenses.