1. In your terminology a dangerous fail is akin to administrative.
2. The law changed a couple of years ago. If your car has a dangerous fail you would only have to drive past an ANPR camera for you to receive an automatic fixed penalty for driving a car that has a dangerous MOT fail. No inspection is required.
1. That is absolutely not what I said but if you want to be argumentative that's fine.
2. The law still focuses on the concept of roadworthiness.
A car may have had a "dangerous fail" and then been professionally repaired but not yet put through another MOT although it will pass. So it,
(a) had a dangerous fail,
(b) is roadworthy, but
(b) doesn't yet have an MOT,
The only offence committed is "no MOT".