Guessing on flights, based on timing of the pic by Freya (
http://web.stagram.com/p/737689763319279454_224656434)
Leave Lerwick Friday for Aberdeen. (BA 4075, 13:35-14:35)
Aberdeen to London on Friday (BA 1313, 16:45-18:15, or BA 1315, 18:30-19:55)
Spend the night in London, then flight BA 814 to Copenhagen today, 09:55-12:50, which arrived today at 12:30, as per
http://www.cph.dk/en/flight-info/arrivalsAlternatively, they could've done ferry/train back to London. Regardless, I think flight 814 is how they got to Copenhagen.
ETA: Doh. I just realized the timestamp was for my timezone, not theirs. Disregard.