Full terms and conditions:
Valid 3rd – 25th January 2018, Mon – Sunday. Available via eat in and takeaway. Not available via Deliveroo. Upgrade to a Kitchen Favourite for £1.50 per burger.
Excludes the Buffalo & The Mighty. Cannot be used in conjunction with any other offer or GBK app reward. Contact firstname.lastname@example.org if you have any issues accessing this reward.
Valid at all GBK restaurants in the UK, excluding GBK Bluewater, and GBK KidZania and The O2 & Birmingham Resorts World during events.