Almost certainly a lady, not a chap. The overwintered mated queens emerge early from hibernation to establish new colonies.
Many thanks, dje. Would you say this is earlier than usual? Jon
Difficult to tell Jon ... your climate is mild west coast so I'd expect them to be earlier with you than my east coast location (where I've yet to see any this spring). I know they're out and about further South (England). I can't tell from the pic what species it is. Earliest is usually Bombus terrestris, but distribution is not as far North and West as you. Alternates usually fly later. Steven Falk has published an excellent Field Guide to the Bees of GB & Ireland - highly recommended if you're keen to identify them. The queens mate in late summer, hibernate overwinter and emerge - hungry - in the Spring. They need nectar and pollen from early plants to help their ovaries develop. She'll then establish a new nest in tussocky grass or a crevice in a wall.
Thank you, again, dje, for this information. We do often find things which aren't supposed to exist on Ardnamurchan, so she may be the species you suggest. Jon
It - she - has such long wings! But I'm not familiar with Scottish bumbles.