ss wrote

Not being electrically savvy but should the `trip` switch on the mains
meter not have clicked in and cut the current off to prevent a fir
starting.

Its not always possible for the trip in the cu to prevent a fire.

For example, if the butane like refrigerant in the fridge starts
to leak out due to a seal or weld failure and that is ignited
by something as simple as a relay tripping normally to start
the motor because its not cold enough, no cu trip is going
to even notice any electrical problem until the fire melts
wires and produces a short that way, by which time the
fire is well alight and it doesnt matter if the mains is
disconnected, the fire will keep burning.