IO,
Roffa - I had the impression that controllers at London Control, and possibly Gatwick too (i.e. those who rarely if ever provide services to GA especially VFR GA) had some training to understand this.
It's a while since I went through the training system so I'm not 100% sure, but I don't think (nor recall) anything covering the differences between an IR and an IMC rating. It's something a controller based at an airfield may pick up from interacting with local pilots and instructors but, as regards the approach controllers at TC, unless they're one of the few remaining private pilots in ATC ranks I'd be very surprised. Remember there's no need for ATC to know the qualifications of the pilot. ATC will offer a clearance, down to the pilot to accept or otherwise. ATC needing to know or in some way policing clearances based on pilot quals is not a road to go down.
CS
I don't think you are more or less likely to receive a transit whether you are VFR or IFR. It usually is purely based on how busy the CAS is.
We'll have to agree to disagree then. With my controller's hat on it's VFR for simplicity every time.
Also, I don't think 'black books' exist except in the minds of the paranoid
