Many of the EFT Bulldogs were repainted in Black / Yellow after conspicuity trails that led to almost all Training airframes being painted black e.g. Hawk T1, Tucano, Domnie, Squirrel etc.
When Huntings arrived and JEFTS began, the T67s were white. After various trials Yellow uppers and black undersides were introduced.
The Bombardier/VT/Grob Tutor was always white apart from display examples which had additional blue stripes and underside roundel. This scheme was reviewed after the collisions of 2009.
Variations on the Black/Yellow scheme has also featured on UK Police helicopters and RAAF and RNAF basic trainers:
ADF Serials - A19 AESL CT-4A Airtrainer