... picture or diagram of how detection worked...another hole in my knowledge! I assume that Monsal Dale being mainline would have had detection in 1902? Hi Tim, Here is a scan from Raynar Wilson, 1904. This is the combined "economical" facing point lock and detector used on the MR. It is interesting that the detector rod is attached to only one switch blade, and there is no detection of the lock position. I see Mick Nicholson has posted a similar scan on RMweb while I was scanning this. 2_191301_420000000.png regards, Martin. posted: 19 Oct 2017 18:26 from: Tim Lee may be a stupid question... but is detection only required on facing points? posted: 19 Oct 2017 19:06 from: Martin Wynne Tim Lee wrote: may be a stupid question... but is detection only required on facing points? Hi Tim, No. Ground signals controlling movements over trailing crossovers are often connected through detectors. There are some great photos of ground signals and detectors from Mick Nicholson in this ...