The NIP will contain a date of the incident.
That date must be within the last two weeks.
Have you checked your diaries to ascertain who was driving?
I'm really sorry but they are not going to accept that explanation.
The problem is this. It is just plain not credible to say that you can't identify the driver of a personal car within two weeks of the incident.
I realise that you won't know offhand who was driving but the law requires you to investigate and we can all ascertain who had our car, even with shared cars, within two weeks.
Some haulage companies can sometimes raise this defence but not private drivers usually.
The difficulty is this. To use a ridiculous example to illustrate the position - if the allegation against the driver were that he was hanging around outside primary schools trying to abduct children then the registered keeper would find out who he was so fast the world would spin.
If the registered keeper can do it with a serious allegation then they can do it with a driving matter.
Magistrates know that and so don't generally accept that excuse.
Oh yes, nobody expects you to know offhand.
The problem is that the law requires you to investigate and find out and we can all do that with reasonable effort unless, of course, it was a very long time ago and even then it is usually possible.
You don't at this stage.
This is just a S172 request. All you do is identify the driver.
There is no way of knowing really. It could have been a police officer or a report from another driver or a local council cctv camera.
They may invite you in for interview but that isn't common with careless driving.
I would imagine they would just summons if they are going to pursue it.
They will have to give you information then though.