Small warbler probably recently arrived on migration from Africa
No interactions present.
Although leg colour can be a guide in separating Willow Warbler and Chiffchaff, it is not especially reliable.
Thanks for the info, one of my field guides suggested it as a disgnostic -but .....!
Lat/Lng: 51.7811, -2.1947
OS grid ref: SO866091
Part of the Slad Valley walk