OP, pl stop assuming, joining up dots and reading into docs what they are not. Let's just stick with facts and procedure.
1. It is not a Notice to Keeper. Apart from anything else, it doesn't say it is.
2. Read what it says, which is that 'You have been named as the driver of the vehicle'. It also states that 'they[the Driver and Vehicle Licensing Agency] have provided the details overleaf[presumably those of the addressee as no others are mentioned]as those of the registered keeper..'.
3. Its title is 'Parking Charge Notice', but given that the only relevance of this term is within the Single Code of Practice(non-regulatory) and Schedule 4 to the Protection of Freedoms Act 2012(statutory) and that the so-called PCN fails to meet the minimum standards under either, then it has no statutory effect or relevance under the Code.
I suggest you do not treat it other than it deserves which is to deal with it relevant section by relevant section and do NOT start with the presumption that it is a Notice to Keeper.
Dear Sir,
Your Notice headed Parking Charge Notice dated 8 October 2025
I refer to the above which was received by me on ****, approx. 4 years and 6 months after the events to which it refers i.e. an alleged 'contravention' by the driver at the time in June 2022 and your claim that they owe you £100.
The notice further states that 'As you have been named as the driver, you are invited to pay the charge' and then, rather confusingly, goes on to say that the DVLA have provided the 'details overleaf', presumably those of the addressee, those details being held by them on their list of 'registered keepers'.
So, although you say that you are writing to me as the driver, because someone has named me as such, nonetheless you are using DVLA data. I'm certain that the nonsense of these conflicting statements is not lost on you.
In any event, I will not be accepting your invitation to pay and would instead invite you to not send me any further correspondence other than to acknowledge receipt of this letter.