The RAF do indeed love aircraft paperwork. But one of their faults is that they don't actually like holding it as an archive or using the data it holds for some good reasons like developing/modifying systems and such like.
It appears to me that there is some naivety in some of the above posts.
If, as I believe, the contracting company was working under the MOD maintenance rules for documentation before the MAA regulations were malformed/created, that organisation was then perfectly entitled to destroy any maintenance documentation over, perhaps as little as, one year old or that had susequently been repeated. This means that the gliders would, if administered as per the regulations at the time, have only some mod record cards, a few recently closed job cards and the F700...
The fact that companies were allowed to do this is purely an MOD issue. not a contractual issue. I am not sure if this rule has been revised....