Other things have been happening which don’t immediately affect the structure of PRNB. The first examples of what may become exhibits in the museum section are being worked on.

Assuming we are able to get listed building consent for the necessary modifications, we aim in due course to open part of the box to visitors routinely so we’ve started to write software for the simulator itself. The requirement for the simulator is to detect the operation of the signal frame levers in the signal box and show on a visual display - the track diagram - the resulting effect for each signal and point. In addition it will need to simulate the approach, arrival and departure of virtual trains which will be under the control of the simulated signals and points. Eventually it is hoped to control all the relevant block shelf instruments in the same fashion as real life.

We’ve done some experiments regarding how to sense the position of the levers in the north end of the box. This is a vital requirement if the simulator is to work so that the public can experience what it was like to be a signalman when the box was in it’s prime. With over ninety levers to monitor for ‘normal’, ‘reversed’ and ‘in motion’, the method which will finally be used has to be both sophisticated and cost effective - not an easy task to find a solution. At present an optical system is the leading contender.

Princes Risborough North Signal Box; Reconnection (2018/9)

The Chinnor & Princes Risborough Railway Association is a registered charity, number 1016237. It and the railway it owns are operated, managed, developed and maintained entirely by volunteers.

©PRNB 2019                                         Updated: 13/02/2019                                                     E&OE

Since August 2018, our steam trains from Chinnor have been calling at Princes Risborough station. Even now it is still an enthralling sight from the signal box to see the engine quietly smouldering in a haze of steam at the end of Platform 4 before suddenly breaking into roaring ‘barks’ of power and towering plumes of white smoke as the driver opens the regulator and pulls slowly out of the platform.  

Now the tracks are down, the platform is open and we’re running regular weekend steam train services, our attentions have urgently returned to the reinstatement of the Princes Risborough North signal box back into working order. A large part of the structural repair is done, although some further work is needed and painting continues apace.

Another exhibit currently being worked on will bring the sound of bells back to the box. Back in the day, signalmen in adjacent signal boxes communicated the type and position of trains on the line by Bell Code. It could communicate other things as well such as ‘Opening signal box’ or ‘Police assistance urgently required’. Network Rail have made available a data feed on the Internet which gives (amongst other things) train position information. We are taking this feed and “translating” it into bell code and using that to give a real time indication of trains moving up and down the main line as if all the old signal boxes from Wycombe West to Ashendon Junction were still in use. At present it uses a computer to make the bell sounds but it will, in time, use real Block Bells.

Last year the 'run round' loop and associated point work were completed thanks to the sterling efforts of our Permanent Way team, but we weren't able to use them until they were safely controlled by the signal box. This meant we had to run our trains 'top & tail' as we couldn't release a single loco to run around and couple back on to the other end of the carriages ready for the return journey. This in turn put even more pressure on our already stretched engine crews.


Step forward the Signal & Telegraph Department! S&T volunteers have been working flat out, some for three days a week, getting the necessary point rodding in place, complete with cranks, compensators and the bases, or ‘stools’ they sit on. Just before Christmas the final tweaks were carried out and the facing point locks adjusted. These locks prevent the points from moving whilst a train is running over them. The pair of points that form the crossover just outside the signal box are now complete and once again controlled by levers within PRNB signal box. Safety testing is complete and the points commissioned. Inside the signal box, the clanging of point levers (and the grunting of signalmen) will once again be heard. There are only five levers (out of 126) now working which may have been the source of rumours that we may be applying to the Guinness Book of Records for the title of “World’s Largest Ground Frame Hut”….

At the time of writing, the disc signals that work in conjunction with the points are being installed but are unlikely to be connected and working in time for the start of the passenger season. We will of course still be able to operate because "Stop, Await Instructions" boards are in place where the signals will be and the signalman will authorise the movement of trains by using handsignals.

All this is, however, only temporary. The levers that control the points are at the wrong end (the North end) of the signal box. In due course we will replace/rebuild the missing interlocking under the South end of the lever frame and operation of the points and signals will be done from there. Presuming we get Listed Building consent, we will  reach the stage of opening part of the box as a working museum and then it will be the South end which controls the railway. That day is still a way off and exactly how far depends on the number of people who come and work alongside us, in our efforts to bring back the all-but-disappeared days of manual signal boxes and steam railways. Please volunteer to join us; we will make you very welcome. You don’t even need to be physically at the box to help out; if you read on you’ll see that a lot of work goes on off-site.