KLM flies to Aberdeen, Belfast, Birmingham, Bristol, Cardiff, Edinburgh, Glasgow, Inverness, Leeds, London, Manchester, Newcastle, Norwich, Teeside IIRC.

Does BA fly on its own metal to all those airports? If so, then which other UK airports does BA fly to beside the above KLM ones?

I mean we could get into a discussion about the status of Gibraltar, but are there any when Gibraltar is not the UK?

BA lists at least these:
Aberdeen (ABZ)
Belfast City (BHD)
Cambridge (CBG)
Edinburgh (EDI)
Glasgow (GLA)
Inverness (INV)
Islay (ILY)
Isle of Man (IOM)
Jersey (JER)
Kirkwall (Orkney Is) (KOI)
Leeds Bradford (LBA)
London City (LCY)
London Gatwick (LGW)
London Heathrow (LHR)
London Stansted (STN)
Manchester (MAN)
Newcastle (NCL)
Newquay (NQY)
Norwich (NWI)
Stornoway (SYY)
Sumburgh (LSI)
Wick (WIC)