First of all thanks to those of you who commented on the previous post either through this blog or on birdforum (mystery acro at knockadoon)
The concensus seems to be that the bird is a Reed Warbler. A Blyth's Reed or Marsh would have been nice but it is more important to have identified the bird correctly.
There are several things I'll take from all of this. First of all there's the learning aspect. What good would it be if I had learnt nothing, Unstreaked acros are very subtle birds especially if they're not singing. I now know at least something about separating juvenile Reed, Blyth's Reed and Marsh Warblers in the field. I have no doubt that'll come in handy some autumn.
Second of all, don't ignore your gut feeling. Based purely on 'jizz' and initial impressions I had this bird as a Reed Warbler. I know you can't base your ID on gut feeling alone but it plays some part in the overall picture. Given that I have seen many Reed and Marsh Warblers in both Ireland and Latvia, that gut feeling would have arisen from my previous experiences with those birds no doubt.
Lastly, when I first realised it was an unstreaked acro I was hoping that it could be a Blyth's Reed (Paddyfield didn't really cross my mind). Why was that though? Well, to my mind Blyth's Reed has a greater rarity value than Marsh. Up until 2006 there had been no records of Blyth's Reed in Ireland. The first record was of a bird initially identified as a Reed Warbler and subsequently re-identifed as a Blyth's Reed based on a review of the photographs. This made the 2007 Mizen Head bird the second record for Ireland having been the first record at the time of discovery (does that all make sense?). Since then there have been regular records almost each year and in 2012 to date there have been four reports of Blyth's Reed Warbler (Inishbofin, Helvick Head, Tory Island and the Beara Peninsula). Still a great bird to find but if you look at the past six years perhaps not so rare. Whether that has anything to do with better awareness or a genuine increase in the numbers of Blyth's Reeds reaching Ireland I have no idea. Their range does appear to have expanded westwards as far as Poland. Marsh Warbler on the other hand is different, at least in recent times. It breeds as close by as Holland, France and Belgium (there was a very small breeding population in the UK but that may be all but gone). However, inexplicably, it remains rare in Ireland. As far as I can recall, in the same period of time (i.e. since 2006) there have only been two records. One was in 2009, a bird ringed in Norway as a Reed Warbler but subsequently trapped on Cape Clear and re-identified as a Marsh Warbler. I twitched that bird and it was a real skulker. The only other record I could remember was of a bird singing at Kilcolman Marsh in Cork in 2010 (I'm not sure if that record has been accepted yet by the IRBC).
So I guess the point I'm making is that if the bird had turned out to be a Marsh Warbler rather than a Blyth's Reed that would have been a little bit more unusual and may have been a catch-up for some birders. It's all a moot point in any case because it has turned out to be a Reed Warbler after all.