Not to piss on your parade mate, but they have up to 6 months to issue a summons to get you into court.
I found out the hard way and the summons was issued to me to attend 1 day before the 6 month period was over.
So in total it's
6 months + 14 days before you've deffo got away with it.
They don't have to prove that the NIP was delivered either, only that it was issued from their office within that 14 day period.
I'm sure that if you haven't had it within the 14 days then you'll probably not get it, but just wanted you to know the facts of the law so if it does happen then you won't be under the illusion that it's not legal.
It`s only 6 months if you have been pulled by the police as they have to verbally tell you that will be happening afaik. Its normally 14 days for a camera issued NIP and only from the time that it was stamped to go out as already said but they cant do the 6 months thing via this method again afaik.
Just checked up on this and as I understand it you could be right.
If it is issued on the 14th day after the alleged offence then that can be a "Time Elapsed" NIP and can be dropped if you use the correct wording in a letter.
The law states that it has to be posted with the intention of it arriving to the Registered Keeper within the 14 day period using oridnary post.
Quote from Pepipoo website
"So, if it's more than 14 days since you were flashed, then they're too late to prosecute you - unless you were driving a company car, hire car or someone else's car. In those circumstances they're allowed more time to track you down."
"If you were stopped and spoken to by a police officer, they have 6 months to prosecute you because the officer will have issued you with a verbal NIP at the time."
So mongo, it looks like you are correct on this.