BA have, for at least the last 15 years, regularly gone out for quotes for ground handling at their UK regional airports (i.e. not LGW and LHR). The quotes are always for all BA GH. All the big boys have quoted numerous times.
Correct me if I'm wrong but Swissport NCL are the only GH agent handling BA mainline in the UK and this is an historical issue going back many years from the formation of NorthEast Handling with ex BA staff.