AD
I think I'll stick to the advice of the CAA inspector in my teaching, thanks all the same, and keep the circuits tight where possible.
You clearly don't fly with a great variety of people if you think that no-one will be flying near an ATZ without contacting the airfield, and a posthumous accusation of bad airmanship is not going to do you much good. Your good airmanship of staying, where possible, in the ATZ for circuits will!
Certainly 4½ nm from the airfield is outside the bounds where people can be expected to be complying with the circuit pattern unless within controlled airspace. I would happily pass this distance from a small airfield like Cranfield.