As a signalman from long ago, it was always the principle that most out of the ordinary cautions were given as late as possible. This would reduce the possibility of the driver forgetting, misunderstanding the location, etc. Now I realise that you have all sorts of means of communications and aids nowadays, but it is a simple way of avoiding an incident. It may cost the train a few minutes delay, which is very important to some, but it is a lot safer than the risk, albeit tiny, of a serious incident. The latter mattered a hill of a lot more on my day than saving a few minutes.
The most that might happen was telling a driver something on the lines of, “You will be stopped at signal AB123/Little Womblings’s Home Signal. Call the box straightaway.” This would avoid the situation where a train came to a stand and the driver just sat in the cab until the signalman’s frustrated swearing got so loud that he could hear it.