I decided that a small signal-box or ground frame is required.  I assume that it should be located somewhere near the bridge end of the layout in order for the imaginary signalman to exchange the imaginary staff or token with the imaginary driver or fireman of all trains arriving or leaving.  A box mounted on the platform would be ideal but is probably out of the question as the platform end near the bridge is already rather crowded.  That leaves the area of ground which is currently occupied by the lineside hut. I am pondering whether to locate the box adjacent to the hut.

:hmm

Whilst perusing my copy of Southern Signals by G.Pryer, I came across a beautiful 'Brighton' ground level signal-box formerly situated at Adversane Crossing, situated between Billingshurst and Pulborough.  In the photo, the signalman is obligingly stood outside the box which gave me a rough idea of the dimensions.  Here's a rather cruel close-up of the box under construction.  The box measures 44mm x 38mm.

If the box is situated adjacent to the lineside hut, the observer will be looking at the plain back of the structure and ends will also be on view.  Sadly, the front will not be seen.

More soon.

The hut could be re-located further along the track, assuming it can be prised from the baseboard without damage.  It's glued down with PVA.  I also picked up some useful information regarding point rodding, signal wires, facing point locks and ground signals, all to be put into effect at a later date.