There is only an obligation upon the police to serve the NIP within 14 days upon the Registered Keeper or driver if known, it DOES NOT apply to anyone else thereafter. This may result in the notice being received extremely late after the offence. You may as a result be unable to identify the driver. If you are a company you will be expected to have documentary evidence of who is driving which vehicle at any time so the delay is less likely to provide a defence but for private drivers it is possible this could amount to a defence. This aspect of the NIP is very complicated and you would benefit from some expert advice at this point.
You have confirmed that you did not receive the NIP within 14 days and that you are neither the registered keeper of the car nor were you the driver.