The City of London has an on-going initiative to promote business in the downtown core of the City with a promo code that can be used only through the HONK system (not applicable to machine or kiosk purchases).
The promo code CORE can only be used once per day, per account and per vehicle.
CORE is only applicable to certain zones in the downtown core, and is not applicable to City of London lots.
If you are having issues applying to the code see the screenshots below for reference or contact HONK support.