Shack37
I think BA have employees from many independent non EU countries unless of course Singapore, Malaysia, Japan etc have recently joined the EU without my noticing. BA may also cease all operations to EDI, GLA and ABZ but I have doubts that they will.
Then if working and based in the UK they must either have the right to work in the UK by birth/relationship or have a work visa which allows them to work in the UK - if they have neither then they are working illegally. BA may have staff working in other countries who are not entitled to work in the UK which is fine so long as they satisfy that countries work requirements.
BA(BEA) used to have a Highlands and Islands division - Viscounts VFR into Benbecula in poor viz anybody
I suppose a Scottish passport holder could work for a Scottish division of BA but not one which may require you to reside and work in the UK.
HF