Chris wrote:

1. Flickering light. I checked behind the switch and found that the
earth wire had come loose. Reconnecting it solved the problem.

Possibly a loose terminal screw on the switch too, which you disturbed
enough to restore good connection (for a while, anyway).

2. We have two lighting circuits in the house (upstairs and
downstairs). The fuse blew on the downstairs circuit. All the lights
in the house stopped working, even though the fuse for the upstairs
circuit was fine. Replacing the blown fuse brought all the lights back
to life. Subsequently, removing the fuse for each of the circuits
individually gave the exepect result - only the lights on that circuit
stopped working.

Very strange that one. A loose connection inside the consumer unit or
fusebox might account for it. Knowing what caused the fuse to blow in
the first place might help, as would some idea of the age and type of
wiring involved.

I think you'd be well advised to get a Periodic Inspection done by a
competent electrician. Loose connections can lead to fires.

--
Andy