Thanks Grant. I already have a separate spur, as there are no ring mains in France.
There is also a “Linky” Smart meter in just about every house that will also add noise to the mains.

It may be more apparent in the evening when the LED lights are on, and the heating is working more. I shall investigate further, but this may just be something I have to live with.

It is not new, but it is starting to annoy me more. It has been colder recently, so it may well be heat pump related.