Thanks for that JHB/Andy. I am puzzled by this car for several reasons. At first it all seemed quite simple, but the more I look into it the more questions I have!
For instance, a friend showed me an interior drawing of one of the West Clare Drewrys which I thought would be all 2+2 seating with a central aisle, but it seems it was not all that way. There were bench seats at the ends facing into the car and two rows of double length seats just in from one of the doors were back to back, covering the engine. Ok this was a 4-wheel railcar built slightly later, but it makes you think!
The D&B car also has an odd entrance arrangement with the recessed doors, which doesn't quite seem to fit with a regular 2+2 arrangement somehow.
I guess the engine was at one end, between the driver and the passenger entrance, but I can't be sure. Why did they need a separate door for the driver? Was it because the engine was in the way? Was there a driver's door originally at both ends? It is so easy to make assumptions!
There was a family of these 2-4-2 railcars, with one for the Kalka Simla railway and several for Tasmania. There were excellent large scale detailed drawings of the Kalka Simla car published in 'The Engineer', including a sectional plan of the chassis showing the controls and other details. This is a smaller vehicle than the D&B one and had a semi-open body supplied by Drewry, with seating right across the car and separate doors for each row of seats. The driver and engine were in a separate compartment at the front. The Tasmanian ones were all bodied in Tasmania, but they too had a quite large separate compartment for the driver and the engine. The D&B car had a smaller engine than the others.
If the worst comes to the worst I will have to brainwash myself, or at least pretend I didn't find all these things out - that way I can model the railcar with all 2+2 seating with a clear conscience