Creating a DMU would be just like creating any other product - it would be hard to image how it would look and feel from a paper drawing. It would be hard to test the ergonomics. So for these, and for other reasons, mock ups of parts of DMUs were created, and some of those are featured here.
In the first two images a portion of a Met-Camm vehicle has been created, possibly to try out the styling of the seat with the paneling, or even just the shape of the seat. As well as satisfying the firm's own staff, often B.T.C. approval would be needed as well on certain aspects of the design. These were taken during the construction of the 79xxx vehicles.
A mock-up of the revised (ie after the Lightweights) Derby standard cab. Little else is known about this image other than it is dated late '57, and in this condition it is unlikely to have been used as a mock-up before building the vehicles, although it's original purpose may have been that before being updated. One use could be for staff familiarisation as Derby also had a training school, and the cab interior looks pretty complete. One big difference in the mock-up is the visible door into the cab is hinged on the opposite side from normal.
While the design panel had influence in a lot of DMUs, this was normally limited to items such as colour co-ordination of interiors. But by the time the Trans-Pennine units were built they were given much more control, and an external industrial design consultant was used. These two images of a Class 124 mock-up served not just to try the cab layout, but also to pick the best location for the four-digit route indicator on the outside, with it being tried on the front of the roof dome.
As well as for design use, mock ups were built for promotional use. A Derby Lightweight cab has been seen on the back of a lorry during a fair in Derby, and a Blue Pullman cab in Repton college for an open day. This wooden mock-up, numbered 51401 contained a cinema which seated 62, an information bureau and "sectioned scale models which operated at the touch of a button". It was built for the "Boys' and Girls' Exhibition" held at Olympia in the early '60s.