I eventually found a suitable sized control box - a weather proof metal letter box. Nice opening door, the controller I use sits inside quite nicely. Piccies below show it in place and the conduit for the switch and power wire layed out ready, lots of annoying work to take up of paving slabs to keeps the conduit out of sight.
In the station area the conduit will sit under the ballast. The track has to be taken up to attach the switch and power wires, so a bit of work to do - I wish I'd done it when I layed the track orginally.