Lancaster's patent watch camera was the subject of British patent 12,571 of 4 October 1886. The camera first appeared in a commercial form in 1886 and from 1887 two sizes were being sold giving negatives of 2 x 1½ in. and 1½ x 1 in. The early models had simple rotary shutters turned by hand which were replaced in 1890 by an Improved-pattern camera with a simple drop shutter. An example of the Improved-pattern camera was sold in 'Spy', Subminiature and Detective cameras, 9 December 1991, lot 219.

The Ladies-pattern camera was the original style of camera and is that illustrated in the patent specification. The principal features of this design which differentiate it from the later patterns are the special plate holder, shutter and opening rear door. The special plate holder allowed for single exposures and was slotted into an aperture in the back of the camera while the later cameras had a standard aperture for holding a conventional single metal slide.

In this example the plate holder takes a 1 x 1 in. (approx.) plate and not a 1 x 1½ inch plate which is normally ascribed to the Ladies-pattern watch camera. Contemporary advertisements are ambiguous about the exact plate size the camera took and listed three variations of the camera at various prices but without giving detailed specifications.

The Ladies-pattern Lancaster watch camera is considerably rarer than the larger sized and Improved model. Auer (1989) states that 'Only two known examples exist'. This is a third example. The other two examples are held at the International Museum of Photography at George Eastman House, Rochester, New York and at the J.C.I.I. Museum, Tokyo, Japan.