Update on this.
Due to the recent regulation changes on rental properties of which I’m currently in, the electrics have to be tested more stringently.
This house does have DC filtering in but worse, the wiring has failed the test. The landlady doesn’t want to spend out on a complete rewire to rent but to rewire to sell!
So wish Covid and Brexit hadn’t screwed the market because both mine and my partners houses would have sold by now and we would be living in our chosen area rather than having to look for another rental property.
We can’t live in our houses because both our exes are in them!
At least we know the cause now tho. Worst still, I might have to sell my beloved Luxman to raise some rental dosh!