Update...
Electrical stuttering was getting worse and I could now hear definite crackling coming from the box that connects to the meter. And it's next to the gas pipes and meter. I phoned EDF again, and told them I'm not leaving this overnight. A different person this time agreed - was it because I've now identified it's definitely their responsibility, I wonder(?)- and sent someone around within half an hour. Although he seemed better than the first bloke who didn't seem to give a toss; definitely sounded like it's would have been tomorrow otherwise.
Electrician was nice chap, but he tried but couldn't pull out the 'thing' in the plastic box because the lower contacts were welded (this is all live!
. He said he wouldn't be able to get it back in again if he did and we'd lose power, so someone's coming tomorrow at 9 a.m. to put in a new whole box 'thing'. Said the problem was a pin-size hole causing a spark which heats and expands..vicious circle.
BTW, he said he personally works for both parts of EDF and can do meters too, but some others can't. Most confusing.
Anyway, mind's at rest: there'll be a bit of flickering overnight, alright as long as it's not overloading (shouldn't) and smelling/getting hot (if so I have to turn off consumer unit).
Woffling, but thought someone might be interested (and it's therapeutic).