Do any of the more recent systems give any indication of what it's going to do before it actually does it? I understand that that's one of the problems with intervening - by the time you know that it's going to do something baffling, it's already done it and it's then often too late to do anything about it. From conversations that I've had with signalmen though, there does seem to be a reluctance to intervene even where it is possible. The most recent example was when the "wonderful machine", as the signalman put it, held us - when we were ready for a right-time departure - for a late-runner that didn't arrive in the station, without conflict, until a couple of minutes after we should've left, and wouldn't have been ready for another three or four minutes as the driver needed to change ends (we were both class 1 with no station stops or conflicts before our paths diverged a few miles later). That does fit with
@contrad!ction 's suggestion that they tend to give priority to late-runners, but in this case it would've knocked us for 7-8 minutes vs no further delay to either service (in the end, the signalman
did intervene, but we were already late by then and subsequently knocked the other service as a result).