Hello Ken,
a Willow Warbler for me too. Good head pattern for this species, strong bill with extensive pale/flesh lower mandible (I even thought about a Melodious Warbler in one picture), better colours than or Chiffchaff.
Maybe some moult issue? A quick look seems that P2 (and appears worn/faded) is longer than P3, which means that at least P3 is still growing (or is it to much wishfull thinking? Its a hard picture)
And more: a good example for a pitfall picture: I even thought that maybe more than one bird was envolved, but this might be explained by distortion caused by te window?