No internet for around an hour. Half of that was spent waiting for VM to answer the phone, then do tests. He ended by saying he would get a new modem sent out. 5 seconds later the internet returned. DOH!!!
It went off again later, and resetting it caused the main RCD to trip. And again a couple of hours later.
(P.S. the missus is suffering a period of insomnia, so is up on the net most nights)