Forensic Architecture, folks.
To my eyes, it looks like the original dormer on the right (you'd often see worse) has been extended to accommodate the home of a son/daughter + their family.
Now, why they've done it as they have is a curious one.
From the shadow line, it appears that the south side of the house is at the leftmost (ugly) gable.
And it seems that sunlight into the bay-window room was a 'design imperative', as they say.
Now, the rest of the ugly end I am not sure of.
It may be that the original intention was to set all the new block at right angles to the existing dormer.
That would 'explain' the Dutch hip above the bay window room -- "in sympathy" to the dormer's roof pitch.
But then they must have wanted more space than a decent length would allow; so they then just fattened the new block by extruding out the mid-section giving Mam + Dad sunlight up there through most of the day.
It's classic architectural technician in its features. Few arch techs would have produced as poor a 'solution' to the spatial arrangement problem though. In that way it's more reminiscent of the old designed by its builder type farmhouse seen across the country from WW2 to mid 1970s.
It was not necessary at all to have such a high garage and the Dutch hip on that, to me, makes the whole sight even worse. Car access from the rear would be better too.
I'm pretty sure this is not the work of O'Donnell Tuomey.
I assume you are vexed at some of their work in rural villages, e.g. Galbally.http://www.odonnell-tuomey.ie/webpage/g ... vista1.htm
Reminds me of the Park Hill estate in Sheffield.http://farm4.static.flickr.com/3383/350 ... 6f6746.jpg