The Glow-worm control electrode causes the spark that starts off combustion within the appliance and is also responsible for monitoring whether there is a flame present in the burner. This is an important safety device that makes sure the boiler isn't still supplying gas without a flame.
Supplier part number is 0020061573
Technical specification
TypeElectrodeERP RatingNot ApplicableSupplier Part Number0020061573Brand NameGlow-Worm