Another Black Redstart

Setting off on a circular walk of the Angle peninsula (hoping for an early Wheatear), we found a very dapper male Black Redstart in the car park at West Angle Bay interacting with its cousins - Robin and Stonechat.
Later,very much later, for there are some very steep sections along this glorious and dramatic section of the Pembrokeshire Coastal Footpath, we watched a flock of 6 Chough playing "tumble fun" above East Pickard Bay. The "ring" leader sported a yellow band on it's left leg. We could not be certain of the lower band's colour: black perhaps? Definitely not blue ,red, orange or mid- green, but certainly very dark. We would like to know the bird's history if at all possible.