Landships II

A few years ago I lost my file of research materials on the British Heavies due to a rather messy plumbing disaster ... Anyway, when I contacted David at the Museum to replace what I could, he mentioned that while there are "works drawings" for the hull of the Mark IV and others, none exist for the sponsons.

I'm curious whether they really don't exist anymore, or whether they're just located somewhere else.  Refer to the thread about the interesting artefact connected to the Mark I.

Comments?