Please can someone identify this bird?

Please can someone identify this bird? It flew into my next door's out house sometime yesterday evening - they noticed it when they went to lock up last night. They left it out this morning and they seem to think that it's a Sikin but it doesn't look like a Siskin to me the colours don't seem right, not enough black on wings, no stripes etc. But I do have loads of Skins coming to my feeders. To me it looks like amaybe a Warbler of some kind or even a young Grey Wagtail lol. Just not sure. Sorry about the pictures but they were taken on their camera phone in artificial light, any help would be greatly appreciated.