It's not a s172 notice. It's a NIP for the driver, which has reached the driver at the time of the offence. The OP can't say that he didn't receive a NIP as he did. This isn't a loophole he can argue at court.
Indeed. It is strange how they got it right, but ultimately, they have correctly served a NIP.
Out of interest, what would be the situation of their guess was wrong and the NIP was incorrectly issued?
Still seems bizarre that they would firstly guess at who was driving rather than ask and secondly actually get his details from somewhere, as presumably the insurance is the only thing linking him to the car, and 7th to 9th seems very fast to get that info from them.
Personally would still be doing more to verify it is actually legit, just seems very quick and conveniently correct for something genuine, rather than a prank or scam or something.