A couple of points:
- Quorn GCR Up platform down starter: In a conversation with the head of S&T, I was told it was a conscious design decision to fit a mechanical colour light (it is indeed a spectacle plate behind a single lens, electrically lit, operated by the usual lever and wire semaphore method - balance weight, crank, etc are under the platform). There was limited room for a semaphore alternative (well, perhaps e.g. a somersault arm would have been OK) due to passenger heads being at risk! The signal is only used when up trains that have terminated from Loughborough need to reverse, mostly Thomas shuttles and other special events. The trailing crossover north of the bridge had an FPL added to allow this as a passenger move. It was added some time after double track was reinstated. And yes, I'm a former S&T volunteer there! Sadly no time these days...maybe again in future. One can hope.
-single lead junctions / single ladders: In the 1980s or earlier, it was decided at a high level that to reduce maintenance costs, junction design should minimise (a) the number of times a switch is moved, and (b) the number of crossings, even if the number of switch ends increases a little. Apparently the maintenance cost of a switch end is lower than a crossing. A single "point" has one switch and one crossing, a diamond crossing contains 4 crossings (including 2 more costly obtuse crossings). A classic double junction has two switch ends and 6 crossings, 2 of which are obtuse. A single lead has 4 switches and 4 crossings. Apparently this is cheaper in maintenance and capital.
- Flank protection: To save wear and tear, and to reduce the risk of a failure (which is a risk every time a switch end moves), it was decided that unless there is a very good reason, a switch should lie in the last position set until a new route is called and set, not returning to 'normal' after a train passes. This improves efficiency in many locations and reduces the number of operations significantly. SPAD induced collisions weere deemed low risk given AWS, longer overlaps, and modern brake capabilities. The benefit was deemed to outweigh the risk, and given the pressures on BR costs at that time, who can blame BR's people? Since a few incidents culminating in Paddington & Southall, the practice of providing flank protesction has become more usual again at risk locations. 'Tis a safer practice and generally life has a higher value these days. Social change and all that...H&S has its place for sure.
Hope that explains the background, at least as I've had it reported.