Don't you recall all those cases years ago with early breathalyser stops ? IIRC the law said "when stopped by a police-officer in ( full ? ) uniform " and then there were endless legal arguments about whether the law was applicable if the officer wasn't wearing his hat/cap which meant ( so the argument went ) he was not in uniform and the stop therefore invalid.
I think any distnce would pass according to the letter of the law and/or cops/CPS wouldn't try to prosecute.
Back in the 'eighties a work colleague who was an ex Met. motorcyclist told me that a traffic stop by him was not valid unless he removed his helmet prior to speaking to the vehicle's driver.
About 2 hundred in my case & I guess around 20 years.
Servicing & repairs as well, first name terms with the staff & I've never been ripped off .. no reception desk, courtesy car or bull...t
Family run rural garages are a virtual goldmine these days.