Teesmouth Bird Club

Having sorted out Pipits in my mind after a previous post - thanks to all who contributed - I'd like some help with another. If they aren't sitting singing I have great difficulty with Chiffchaff / Willow Warblers. Attached are a few photos. Which do you think are which - or are they all one, or neither?  Another posts with pics to follow

Thanks in advance.

Not the easiest of photos to say for sure the leg colour doesn't show well nor the wing primary projection. I'm tending towards Chiffchaff as on one photo the leg colour looks dark and the primary projection on another looks short.

Thanks for the help Ian. A, B and C were all the same bird and the only one that was identifiably making a useful noise. It was, as you accurately surmised, a chiffchaff but your answers will help me in future when they refuse to identify themselves.