Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Pilot ON
Summer/Winter Switch set to Summer.
HW Thermostat to Max (fully clockwise).
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Turn HW tap ON.
Does boiler light to high flame ?