UKC

On an East Lothian beach last Friday I spotted a bird that I couldn't ID.  It was about the size of a blackbird - maybe a tad smaller/slimmer but definitely significantly bigger than the stonechat that was perched nearby  - and was perched on top of a post in a rather upright stance.  The plumage was basically a pretty featureless all over brown, but with an definite reddish/russet tinge to it.  I didn't notice any obvious markings like eyestripe/supercilium, spots or stripes on the breast etc.  I failed to make a proper note of the leg colour, or the length and colour of the beak (that might be because they weren't particularly striking or unusual).

Scanning through the bird books since hasn't brought me to a sudden: "Aha, of course it was one of those!" moment.  I had a go with the Merlin app but all the candidates it suggested were species I am quite familiar with.

Help me, UKC birders - you're my only hope!

Did you see it fly - wavy, straight?

It flew off the post after about a minute but as I was looking at it from a beach below the edge of a dune, it disappeared from view very quickly.  There didn't seem to be anything particularly notable  about what I did see of its flight pattern; much same as any small to medium sized passerine*.

Did you have any particular candidates in mind for which the flight pattern might have been a decisive factor?

* It definitely wasn't any kind of raptor, of which Merlin suggested a fair few.

No, not really; can sometimes be helpful though.

The only suggestion I have would be maybe female black redstart - has the bit of reddishness on it, likes sitting on posts, and the size would seem to be about right.