Not a signalling buff, guys, but I have been trying to find information about the old STRAD machines and found this site! I think that STRAD stands for Signal Transmission Reception And Distribution and had something to do with Cable & Wireless. When I joined BR at the end of 1970 as an ATI clerk, I was sent to Eversholt House at the back of Euston Station, to learn how to touch-type and we were taught on STRAD machines. I recall that if you needed to send a message you had to be very prepared as you had to keep the connection open. Stop and you have to start again! It was a system used to send messages about, notices, special traffic movements, requests for empties and other fairly urgent matters. I worked in what had been the old Centre Box at Toton and we had one there and I know there was also one in the Traincrew Office as the guy who operated that one was on the same course as me.
If anyone has any further information, like getting hold of the code book for the system, then I would be pleased to hear from them. Even the NRM at York doesn't know what I'm talking about!
Regards