I will attempt to describe the "Transmitter" mechanism as simply as possible: The clock is controlled by the six time pips sent out by the BBC at that time. The pips were timed to a very high level of precision by very precise clocks kept [and constantly checked against the movements of the stars] at astronomical observatories. Apart from astronomical studies, timekeeping was a major part of an observatory's duties. Most observatories at that time had one or more precision clocks.
A see-saw arrangement of two electromagnets is situated at the very top of the master clock mechanism. These electromagnets lift or lower a regulating weight onto a tray on the pendulum.
Another, separate timekeeping mechanism, in the middle of the clock case, decides if the clock is fast or slow compared with the observatory time signal.
Weight regulation of precision clocks has a long history. Normally, small weights are placed or removed manually onto a tray placed near the middle of the pendulum rod. Sometimes tweezers are used to place or remove these weights to ensure the pendulum is never disturbed.
The genius of Gents' engineers was to use electromagnets to place or remove the regulating weight on the pendulum tray. A clock with a weight added will slightly gain. [Go faster] When the weight is lifted free of the pendulum the clock will change to a slower rate.
If only it were that simple to achieve perfect time control from a reference precision clock at a distance. This was cutting edge technology for its time. An added Relay unit accepts the 6 timing pips sent down the telegraph wire from the distant observatory. This in turn passes on a brief signal to further [time checking] units on the transmitter. The seesaw unit will then be triggered to leave the weight alone, lower or raise the weight depending on the exact timing of the pendulum relative to the precise observatory signal.
Towards the end of the video a bell striking mechanism is also controlled by the transmitter via a series of accessory units. These are shown in action during the hourly strike run. All in all, a fascinating display of a whole series of Gent's timekeeping products in excellent, original [or finely restored] condition.
All of these fascinating units apply electricity to achieve remarkable results once entirely the domain of centuries of mechanical clocks. The increase in accuracy of timekeeping, reliability and the precise control of dials and bells is the stuff of electrical horology. Where a small number of British firms competed in the first half of the 20th century for the world market in improved timekeeping methods. This led to historical changes in timekeeping for the railways, offices and factories as universal timekeeping could be brought, at relatively low cost to every corner of commerce.
For the first time in history every clock dial could show the same time and required no regular and costly repairs for natural wear and tear. Imagine the effect on a huge factory complex where every clocking-in dial showed the same time. Or vast, multistory, office blocks where every wall dial agreed with every other. Where factory machine, run times and productivity could actually be measured and printed out. All without a single man, with a watch and a salary standing over every one of them.