The first vehicle
As with most DMUs, the sets were well described and illustrated in the railway journals of the time.

During the restoration of the preserved set, the owners were lucky enough to unearth some shots taken as the first vehicle, 50415 left the works. They are undated but show that several changes (inside and out) were made between when they were taken and before they entered traffic. 

The same vehicle visited the Battersea exhibition (28-30th June 1957). This Differences noted were in the works pictures the the top lining extended onto the black gutter, by Battersea it stopped when meeting the gutter. Blue squares were now added.

Finally, there is variations in the painting of the underframe items, with more items picked out in silver in the first picture but painted black by Battersea.

A difference with this car was where the vac. pipes come through the buffer beam they are black, whereas white was the norm, yet the coupling parts are white.

It entered traffic in August.

Since notable differences occurred in such a short time, it is not surprising that over the unnaturally long period it took Wickhams to produce just five sets that there were further variations. It turns out that all sets had minor differences when new, but this can allow previously unknown vehicles to be identified in photos, aided by the fact that the sets remained in their originals formations till the end.

Blue Squares All vehicles were delivered with these, and they were either to the inside or outside of the marker lights.
Numbers Wickham seemed to have its own ideas about where to apply numbers! Normally on DMUs numbering was applied centered below a window or between windows. Wickham liked to have these run from the centre to the just before the right corner of a window (left picture). But even more bizarrely, on the first two trailers the numbers were applied to the left side rather than the right. So on one side of the units both numbers were on the outer ends, on the other side they were both on the inner ends! (right)
Electrical Box A lot of the electrical equipment on the underframe is grouped together under the power car just on front of the battery box on the drivers side. On the first car these were all in individual boxes (left), on the other four (right) one large lid covered them all. A similar arrangement was on the trailer cars.

50419/56174
The entries have been left blank as I have not been able to find any photos of these without whiskers. But pictures of these cars with whiskers shows another variance, in that the have the thick lining top and bottom, rather that a thin one on top as was norm for the whisker period. The set wasn't delivered till August '58, and the earliest identifiable picture I have of them is March '59, so they were either delivered with whiskers or they were added very soon afterwards.

White embelishments
It has been suggested that the first vehicle was tarted up with white tyres, lamp faces, buffers, vac. pipes etc for exhibition at Battersea, but there are plenty of photos that show that at least the first four sets were all treated like this when new. Below is a picture of 50416 / 56171 (the preserved set) when brand new, for 50417 / 56172 see the book 'British Rail DMUs & Diesel Railcars' by Brian Morrison, top of page 103. For 50418 / 56173 see the winter 58/59 ABC. White is not the best colour for railway vehicle, particularly on the underframe area, and these soon just got dirty and blended in to the surroundings. The white lamp facings stood out the most, as the lenses would be cleaned. Interestingly the white vac. pipes and couplings was retained in almost all cases right through to blue livery. How did the staff survive without them being blue and red? Its physically impossible to get them the wrong way around!

So can we identify unknown vehicles from the pre-whisker era? In the picture on the right, the blue squares are in the inside, the number is on the left side of the vehicle. Using the table above it must be preserved 56171! Taken on the 18th June 1958.

Some information can be applied to other periods. In the Brian Morrison book the picture of a power car under construction at the bottom of page 102 is 50415 as it has the separate electrical boxes. The leading Trinidad vehicle at the top of page 104 is 56174 as it has the combined electrical box.