My little mate the coal tit is back on the scene, now with a mississ in tow! the 4 pics just about cover every angle for ID purposes!
No interactions present.
by the amounbt of black on the 'bib' of photos one and four, thems the mrs.
males have a larger patch of black.
I would not be confident in sexing Coal tits in January by the bib. I would have thought that what is said about the size of the bib might apply to a breeding pair of adults, but these birds cannot be aged from these pictures. A young male would be similar to a female, for example. A breeding male would have a more glossy bib than a female, but it is not a simple thing to judge.
I suspect there is a lot of overlap, and you would need a sample to see the dfference.
My Flickr photos...
Lat/Lng: 53.5675, -1.4429
OS grid ref: SE369080
In back garden coming to bird table in Monk Bretton Barnsley with the 'other half'