Just to clarify on what dennilson says, you do not have to receive the NIP within 14 days. They have to serve the NIP within 14 days on the registered keeper. Thus, if you are not the registered keeper of the car, it will go to them first, and they have to return it and then the CTO will send an NIP to you.
All the CTO have to prove is that they sent it to the RK within 14 days (and to prove this, all they need do is prove it was correctly addressed to the right person, with prepaid postage and actually posted - unless proved otherwise under s7 Interpretation Act 1978 it is deemed served within 2 days of posting), thereafter the burden of proof rests with you.