Thanks for this informative reply, and since I have a couple of spare minutes I'll reply. Firstly, are you sure about your cycle time of four minutes? That would be exceptionally long for any traffic lights, except at roadworks where they can be very long. Permanent installations tend to be around 2 minutes maximum - I'd suggest that you might spend a few minutes at the junction and time it from the lights going red on one arm, until they go red the next time around on that same arm.
Secondly, your junction is smaller than most in terms of the numbers of traffic lights. At the A5 Emstrey island in Shrewsbury for example, there are many more than this, with most traffic having to pass through more than one stop line on the island. If you take the number of stop lines, and factor in the number of lanes at each stop line, the figure (in my head) comes to at least 20. TWENTY! That's a whole lot of opportunities for red light running, and I suspect that if this was ever monitored then the figure could well exceed my earlier suggested 5000 per day. Note that monitoring is NOT the same if you stand there in a yellow jacket, because driving habits then improve straight away as drivers perceive a threat of enforcement.
One immediate answer would be camera enforcement. For anyone who suggests that this would be expensive, if you imagine 5000 infringements per day at £100 each, that's a mere two days to reach £1million, far more than the costs of camera installation!!! Okay, there are many counter-comments that could be made here, the point is that it's worth thinking about rather than just dismissing, which so many people will simply do, both on this forum and around the country when it's drawn to their attention