economy 7; immersion and storage heaters stopped working

The consummer unit for the offpeak supply is still showing on, but both storage heaters and off peak immersion heater have stopped working.

Could it be a fault with the meter switch?

It could be if none of them are working. Is it a radio teleswitch? Not sure how common a fault it is though

Have you got a multimeter? If so then you could check to see if 230v is present at each heater/FCU. Have any fuses blown/MCBs tripped? If there is not 230v present anywhere on the E7 installation then it does suggest a problem with the supply switch.

It would be rare for all the fuses to blow anyway.

When E7 becomes live (or is due to), watch the meter / teleswitch - they may have an indicator on them which shows they have changed over. They may also click or thump on the boards they are mounted on - the teleswitch has a pretty big contactor (magnetic switch) in it.

If nothing happens at the meter, or you cant tell, see if the E7 board is live - test the voltage at one of the live outputs. Should be 230 ish. If all are zero volts, you have a problem with the teleswitch.

A picture will help us familiarise ourselves with your setup. A lot of E7 installations are done differently.

Turned out to be E7 stuck "on" and main fuse burned out. (Why did it not trip out?)

Fuse replaced by sparky and new meter with integral radio switch supplied by S.E.