I'd say call/email DVLA..
Truth to be told, they weren't of much help with my personal enquiry, but that was due to rather twisted and complicated nature of my question..
They did reply, though (which by itself was a big surprise to me)!
Your case sounds much much simpler. I'm 99% sure you'll get your answer.
For the record, question that I asked:
"How many P3 XC70 were scrapped between 2010 and 2017, what were main reasons of them being scrapped and what was an average mileage for each class: accident/beyond repair, end of life/worn, other, at the time of " death""
Guess what kind of info I was after?