Originally Posted by
alvinlwh
Gate check is a funny thing. I flew SIN-LHR-GLA-KOI last month and was forced to gate check (not that I actually mind) at LHR. Luckily I took a picture of those case as the tag was only to GLA and on arrival, I asked about them and was told that I have to collect them from the belt and recheck for the last lag.
NOTE: May or may not be the same in OP's case from SIN, IDK.
Could the reason behind for BA to check your bags until Glasgow could be that there are no customs facilities at Kirkwall.