They are getting more strict on changes to the V5 when I changed the Engine in my car, the good old DVLA wanted the receipt from the garage that had done the job, or a report from the AA/RAC to say that the car had the engine in it that I said......
I ended up getting a letter from my local garage (on their headed paper) to say that they had inspected the car and that it was indeed fitted with the engine that i had said.....