The Mark I was available in 1959 (possibly earlier) - and had a black body with sloping sides and a prominent square-section lens barrel. There was a two-pin flash connection, the whole thing was much like a larger version of the Coronet 4-4. It had a choice of aperture, one for colour, one for black-and-white.
The Mark II had a flatter, more conventional body with leathercloth covering and added a two-speed shutter, 1/50 & 1/100s with a PC socket for flash. Image format was 16 4x4cm on 120 film.
- Mark I images on Flickr by user Vagamundos