Chiffchaff?

Nothing's chiffchaffing or warbling at the moment - just sounding the same useless little tweets. A friend came for dinner on Wednesday and he said that most chiffchaffs have left by now and willow warblers are more likely to be seen in the open.  That was because I'd seen what I thought was a pair of willow warblers that morning but I wasn't certain - they were happily out in the open. It would seem that they were willow warblers but I'm thinking this might be a chiffchaff - there were two of them and they were skulking in the grasses.