Staff member, A, is on sick leave on account of a physical complaint. Colleague, B, has reported seeing A tagged on FB undertaking an activity and is of the view that if A can do the activity, then she can come to work. A's absence is supported by Fit Notes from her GP. Both B and I know the full details.
Legally, how should I proceed? Colleague B told me this out of the blue, I had not voiced any suspicions. Should I ask B to show me, or just ignore altogether?