Bundles

Physical

The contents of that attache case were in bundles, held together by rubber bands - which had disintegrated.  From a quick look, there does not seem to have been any reason how the items are distributed amongst the bundles; however, the contest are listed by bundle.

The contents of the bundles have been kept together in separate envelopes, but each bundle was further divided - but only when necessary - into three - those items from her son Gervas and his family; those items from her son Ralph and his family (these were passed to Ralph's daughter Mary); and "Others".

There are 76 envelopes in total; except for the "Ralph" envelopes, they are currently in three A4 box files:-

Red - envelopes A to M
Blue - envelopes N to Y
Green - envelopes  Z, 0 to 9, #, $

Thus to find the original of any specific item, it is necessary to know the colour of the box-file, the cipher on the envelope, and whether "Gervas", "Ralph" or "Other".

Digital

Each item has its own Folder, containing the hi-res scans (one for each page of a letter), and transcriptions, and sometimes other files containing explanetory notes, etc.. 

Currently, there are 3,100 files in a thousand folders, occupying 68 Gb.

Obviously, the number of files and the size of the archive will increase as the items are transcribed.  Transcription is currently almost a random exercise !