Thanks for your replies chaps very helpful. I have since read up on the chap who has resorted one of these water trailers. I would have never have found it had it not been for the replies here so thanks again. The club archive holds all sorts of records of what was built but the factory records for government contracts were not highly coveted like those for cars so there are gaps and things have been lost/damaged over the years. We assumed there would only be nominal value, it's more of an information gathering exercise.