In article . com,
IanMayo wrote:

We're in a 12 yr old conventional house, and had our fuse box
moved about 9 months ago. We have no other electrical problems -
to my knowledge.

My wife replaced a bulb the bathroom last night, after which the
lights worked fine. This morning the lights just "went off".

Since the consumer unit is the most recent
change then this could be the initial suspect.

Turn off the supply to the consumer unit. Then
have a look at the wiring to that circuit breaker.
Can any screws be tightened down, or is there any
sign of burning? Check the Neutral connections as
well. Then exercise the circuit breaker a few times.

Whilst you are there run along all connections and
check the screws for tightness.

--
Tony Williams.