How was the Ful-Vue camera different?

Ful-Vue Viewfinder

A few Ensign box cameras pre-date the Ful-Vue, such as the Ensign ‘Box-Form’, the ‘All-Distance’, and the ‘E29′. 
The Box-Form cameras are listed in the Ensign Handbook of Photography (c.1908), which gives the following description:

“The Box-Form Ensign Film Cameras are exceptionally well and strongly made. They give excellent sharp-all-over pictures.  There is nothing to go wrong, and their absolute simplicity makes success certain.” p.36

The Ensign Box-Form 2 ¼ B had an f/11 rapid achromat lens (variants had a meniscus lens), two reflecting viewfinders and a frame finder.
The All-Distance Ensign was introduced in 1927.  It had a meniscus “all-distance” lens, simple T and I shutter settings, two brilliant viewfinders and a frame finder, and a tripod socket.  Models in blue, red, and brown were introduced in c.1929.  In the accompanying manual, Instructions for Using the All-Distance Ensign Camera, it states:

“There are two outstanding features…The All-Distance Ensign Camera, as its name implies, permits of brilliant sharp pictures being taken at all distances in excess of 3 ½ feet from the camera (WITHOUT THE NECESSITY OF PURCHASING A SUPPLEMENTARY PORTRAIT ATTACHMENT).
Second - By a specially designed (Prov. Pat. 27103) internal spring pressure plate the film is held perfectly flat and thus the definition is as good as will be obtained with a glass plate.” p. 2-3

The Ensign E29 Box Camera (c.1930) was a wooden bodied camera finished in black or blue leatherette, with a simple T and I shutter, a meniscus lens and two reflecting viewfinders.  Close-up lenses were available as accessories.
So what about the Ful-Vue?  How did it differ from these earlier models?
Its main selling point was undoubtedly its large viewfinder (pictured).  A glance at newspaper adverts from the time of its release reveal as much.  On 24th March 1939, the Kent & Sussex Courier featured the following announcement:

“The New British Made Ensign “FUL-VUE” Camera takes 12 pictures 2 ¼ square on the usual No. 20 film, has specially brilliant new view finder so that picture can be clearly seen under all conditions.  Adaptable for Views and portraits and fitted with the Time and Instantaneous Shutter.  With a sling strap 25/-” p. 7

The same newspaper featured another advert on 12th May 1939:

“See your Picture at a glance…
Ensign FUL-VUE the CAMERA with the GIANT VIEW-FINDER
Taking good pictures is simpler and certain with the Ensign ‘Ful-Vue’ - the ideal camera for the beginner and the keen amateur.  CLOSE UPS AND DISTANCE VIEWS with the famous Ensign ‘ALL-DISTANCE’ LENS.
Takes 12 pictures 2 1/4x 2 ¼ in. on Ensign standard size E.20 film.
Get an Ensign ‘Ful-Vue’ to-day! Andalways use Ensign Film.  Only 25/-
BRITISH THROUGHOUT” p.7

Chemists were among the primary retailers of cameras at the time, so it was important for manufacturers to convince chemists that their cameras would sell well.  Ful-Vue adverts therefore appeared in issues of The Chemist and Druggist. Such an advert featured on the 4th February 1939:

“NEW ENSIGN BOX CAMERA - Ensign Ltd, 88-89 High Holborn, London, WC1, have introduced a new box camera which is described as the Ful-Vue, the main feature of which being the bigger, brighter and better viewfinder.  This model is very compact, measuring only 4 1/8 by 3 1/8 by 4 1/8 in.  It has an excellent finish in black ripple enamel, and it takes close-ups down to three feet.  In adition, it is economical to use, taking twelve 2 ¼ in. square pictures.  Stocks are available for immediate delivery.” p.122

It appeared again in the same publication on 1st April 1939:

“ENSIGN FUL-VUE CAMERA - A newly introduced box camera that bids fair to achieve a widespread popularity is the Ful-Vue  brought out by Ensign Ltd, Ensign House, High Holborn, London, WC1.  The important feature of this is a super-size, waist-level brilliant viewfinder giving an image 1 ½ in. square.   The camera, which is of metal construction, with all-distance lens is in two-position focusing mount, and time and instantaneous shutter, is designed to take twelve pictures (size 2 ¼ in. by 2 ¼ in.) on a standard 20 film.  Numbering of the exposures is viewed through  a centrally-placed ruby window in the back of the camera, and thus the camera requires no re-numbering device as on certain other models of the twin-lens type.”  p.382

Another advert appeared in the Sunday Mirror on 25th February 1945 and refers to the impact the war had had on Ensign in diverting its manufacturing efforts to the war effort:

“The easiest camera to use in the World is this popular Ensign Ful-Vue Model with its unique Picture size brilliant viewfinder.  When the skill now employed upon the manufacture of Aircraft cameras and similar precision instruments for the Services is available, the Ensign Ful-Vue will be even better, for like all Ensign Cameras the post-War models will incorporate the great advances made by Ensign in Optical Technique and precision Engineering.” p.5