I'm colour blind but have never had any problems in the past obtaining an airside driving permit (including LHR & LGW). I failed the ishihara test as expected and was then given the Holmes Lantern Test which I had no problems passing.
I'm glad to see that progress is finally being made, even if it is slow, it's absurd that people with CVD cannot pass a Class 1 medical (in the UK) despite there being no proof that having CVD has ever contributed to an accident or incident.