Is this a Willow Warbler or possibly a Nightingale or Chiffchaff

On a walk yesterday at RSPB North Warren in Suffolk we were listening to a Nightingale singing in a nearby bush. It stopped singing and the little bird below appeared above us, first picture, then flew a little way off, second and third pictures. We didn't hear any more singing from the bush and does look more like a Willow Warbler than a Nightingale but we are not sure. As for Chiffchaff we hadn't hear any at that point.

Any help much appreciated.