Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Gain access to the mains connector by removing the retaining screw and lowering it through the bottom case
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage at the 'R' (switched live) and 'N' (neutral) connections of the mains connector.
Expect mains voltage.