Next time I go up there I will check if the dangerous drain cover has been replaced. If it hasn't, I will report it and make sure that the council sorts it out.
I just took a look further on. There is a drain cover on the other side of the road which at least has its slots perpendicular to the direction of travel. Unfortunately, there still appear to be gaps big enough to trap a road bike's skinny front tyre. Once again, it is well out in the road. I reckon the road WAS widened in the past!
If I make a report I will include photos of my bike balancing with the front wheel trapped in the slots of the drain covers.