The best and easiest way to find out the history of a civilian Landrover, and indeed the civilian history of an x-military one, is through the DVLA at Swansea. For a fee of just £5, they will send you a copy of all the details they hold on your vehicle. This will include a copy of registration documents including any changes of colour, engines or anything else that they have been notified of. The address is below:
If you know the Military registration number then the best place to go is to the Museum Of Army Transport. If you give them a call on 01482 860445 ,they will check to see if they have your vehicles records. If they have, then for a fee of £12.50, they will send you a copy of the vehicle's Key Card. This gives you details of the vehicles movements, where and when. If for some reason you haven't got the military reg number, then I managed to get mine by writing with the chassis number and any other info you have to, ES (Land ) Census Team -Tech 3b, Defence Logistics Organisation Chilwell, Building 154, Chetwyned Barracks, Chilwell, Nottingham. NG9 5HA.
If you want to get information about when ,and for whom your landrover was built, then you can contact British Motor Industry heritage Trust, banbury Road, Gaydon, Warwick, England CV35 0BJ. Telephone for the prices they charge on 01926 641188.The certificate that I got back did not have as much information as I would of hoped but was still interesting. It was accepted by the DVLA as proof of build date as the log book had been wrong, for the past 27 years it was declared manufactured in 1967. However it was built in 1962 which ment I could get a new reg number without a suffix.So dont always trust your registration documents.