Business UK

Business UK refers to the ground benefits for passengers booked into fare bucket J, the highest, on domestic services. These ground benefits include lounge access, fast track security and priority boarding.

Passengers using Business UK have either paid for the fully flexible fare on a purely domestic itinerary or have a connection to/from WT+, CE/CW or F.

Business on boarding card

BA domestic passengers have 'C' as the stated class on their boarding card. On European routes and as a standard across the world this normally denotes business class.

Was your boarding card issued by BA or another carrier?

If so it might be the case that the other carriers systems do not recognise 'C' as economy (well, 'UK domestic') and 'business' was printed instead.