Is this a Chiffchaff

Is this a Chiffchaff

Observation - Is this a Chiffchaff - UK and Ireland. Description: It's not been easy trying to identify this little bird. Have settled on a Chiffchaff rather than a Willow Warbler but I'm still not sure so if anyone can offer any assistance that would be much appreciated.

It's not been easy trying to identify this little bird. Have settled on a Chiffchaff rather than a Willow Warbler but I'm still not sure so if anyone can offer any assistance that would be much appreciated.