Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Remove ignition lead from spark generator
Place crocodile clip above spark generator as shown in the picture
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Warning: Do not touch any part of appliance during this test.
At the sparking stage of the ignition sequence (when 4 is shown on display) can sparking been seen from the spark generator to the crocodile clip?
Note:
Boiler will attempt ignition 3 times before lockout,
reset as necessary until test complete.