Although I was certainly taught to use the gears to assist in the braking of the vehicle, my 'A' class police driver friend taught me to use their method.
Brake using just the brakes, keep your revs high, then on the roundabout / junction change down to the lowest gear necessary and power accelerate out of it. This apparently gave the police driver an edge on others. I was never convinced though, and when driving manuals I still use the gears in the BSM manner, unless I want maximum speed in a given situation.
If I can recall my Roadcraft teachings Ms Zoom, it was to be ensured that the vehicle was always in the gear most appropriate for the prevailing conditions, and to the speed of the vehicle.
I was taught by a C8 driver ( before it became the CRS) and passed the civilian test in a total of 5 lessons.
When I was obliged to take the advanced course I found myself better placed, as most of the other candidates who had been taught in the standard techniques applicable to the MOT civilian test, found it difficult to adjust to the very different driving style required.
I can still recall his voice on approaching a course change, 'look, mirrors, check gears, brakes, look, mirrors, gear, brakes if necessary, look, mirrors, accelerate to clear obstacle and make all due progress' Indicating ones intentions as appropriate of course. The brakes being the primary means by which the speed of the vehicle was altered.
It became second nature to adopt the following;
brakes = down - gears = up, in terms of having the vehicle at the correct speed in relation to the prevailing conditions (brakes) and in the most advantageous gear to continue with ones progress (gears).
In fact if the gears were inappropriately used, such as to slow the vehicle in the wrong circumstances, one received a slap across the back of the hand with one of those heavy black plastic SO rules.
When driving the Omega (which is not too often) I still use those same techniques, in so far as the auto box allows and I still practice the progress commentary which was a pain the drawers to perfect all those years ago.