Tim Wacher    2018-12-23 (edited) 

Discussion on identity ongoing. Out of range and unusual habitat for flycatcher. White lower underparts not a good fit for Brown-tailed rock chat for which this is more typical range and habitat. Perhaps strong reflected light from rock is affecting appearance of underparts.

Note: Further distant sightings of a pair at the same location on 10/12/2021 strongly suggest these are Brown-tailed rock chats.