Set Appliance State:

Mains Power Off
CH Demand
Heating temperature selector to mid-range
Hot water temperature selector to OFF
Gas On; Pilot On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Allow burner to ignite and CH system to heat.
Does the boiler shut down as CH system reaches its set temperature?
Note:
It may be necessary to reduce heating load by turning off some radiators to reduce time taken for this test.