Can anyone identify this bird - small flock in ireland?
With the new image it is still hard, but I think I identified the bird. I think this is a Willow warbler (Phylloscopus trochilus) which is pretty common in Europe. 

The drawing from the Royal Bird Protection Society (source here) is pretty similar. 



Unfortunately, there are two pretty similar birds living in Ireland which can be confused with the Willow warbler. These are the Chiffchaff and the Wood warbler. Differences are small, the Chiffchaff has dark legs and a smaller eye stripe (both of which the bird in your image has not), while the wood warbler lives in woods and has a more yellow breast (and is also much more rare). The links provide audio files with the songs of each bird, this should help you making a final decision, as they are pretty distinct.