Thank you all for your kind words and congratulations for DD.
She's got over the initial disappointment now - went into Uni yesterday and had a chat with Student Services. She has to e-mail the lecturer in charge of exams and gradings for her school within the Uni as 'having another look' at her result is a possibility and she can't lose (she's nowhere near the cusp of dropping to a 2:2, obviously, so the only answers can be her grade amended to a First, or stay at a 2:1).
She's got a few 'irons in the fire' at the moment, so fingers crossed she gets some good news job-wise soon.