I first became aware of these cases when a year ago Carole Tozer in Queensland sent me images of the Baby Empire which had been used by her father, Victor Anthony Ricketts, on his record-breaking around-the-world flights in 1938. The story of Victor's typewriter and case can be seen here. In the case (pun unintended) of the Baby Empire, this was called a "Traveller's Model De-Luxe", but it's the same design with the same 1929 patent number as the Imperial Good Companion Secretariate.
The typewriter is in very good shape but the case needed a lot of work. I have cleaned and polished all the surfaces, including those of the correspondence and stationery inserts. I had to repair the tongue-and-grove edge joints all around, as well as the very serious scarring of the vinyl lining inside the top of the case. The damage in each case (pun unintended) seemed to have been caused by not placing the typewriter properly inside the Secretariate - as the sides of the case had been forced out from their joints and the top of the typewriter had scarred the lining. But I think that after many hours of work on this, it has come up looking a treat.
I imagine the sleeves on the right side of the top were used for pens, pencils and that sort of thing (maybe also spare ribbons). But one thing still leaves me a bit mystified: the two clasps on the right side of the fold-up board on which the typewriter sits. These do not appear to be in the Baby Empire case. They are not for spare spools. Perhaps they were used to draw up and hold up the board, although that doesn't seem feasible. Maybe they are there to fit another size of typewriter (such as the Baby Empire/Hermes Featherweight) - although one would imagine these cases were custom-made for different brands.
I'd loved to know who designed it, but can find no trace of the patent No 331951/1929.
POSTSCRIPT: From Typewriter Topics, 1909: