My thanks to Rob Hughes for showing me his copy. They used to be in south London. Maybe they supplied the church photographed in Brixton, (see Architecture 8th May 2011, below).
Don't you love a bit of nostalgia? Reminded me of the Anderson shelter we used to play in a kids. Forgive the sod awful photography. It was competing with a muffin from the Deli in Hay. Anyone who's been lucky enough to eat one, knows that nothing gets in the way of that process.
Has anyone seen or even own one of these studios/darkrooms? Could you get in touch if you do?