Were this to be a Canadian aircraft (Which I suspect it is not) I would contact Transport Canada for the information they hold on file for the aircraft, and with their co-operation rebuild the history of the aircraft. I have done this before for the partial loss of required history for a Twin Otter, and Transport Canada co-operated entirely.
Presuming this is a UK registered aircraft, and hearing all that I do about bureaucracy in aviation in the UK, I've got to believe that the CAA retains most of the data you need to get close. They would probably be delighted to use all that data for some good for a change!
If you're really stuck, I'll have further, more detailed thoughts for you...