A lost album connected to the Irwin family scanned by Mary Lennon
One particular, fantastic image of assembled WW1-era soldiers but without any details.
Album has photos of grave of Cpl. F. J. Irwin, 16616 10th R.I.R., K.I.A. 30th August 1916
Although Fred J Irwin was in the 10th RIR, this photograph does not look like the 10th. Some references suggest that the 1903 pattern bandolier was confined to cavalry and artillery, like the RGA, during the war. Members of the FB group - Royal Irish Rifles 1914-1918 - supported my suspicions and so this is likely the RGA.
After only a little digging, the Irwin in question is very likely to be Fred's brother - Henry Edward Irwin - Reg. No. 101472 of the Royal Field Artillery (Unit C - 173rd Brigade) . He signed up in Dundalk and was assigned to No 5 Depot of the RFA at Athlone. He made it to Sergeant and was awarded the Military Medal and Croix de Guerre amongst others. (M.M. gazetted 13th March, 1918.).
The high quality of the image means that the majority of the men can theoretically be recognised so that may help narrow the details down but there is otherwise no date or location. The impressive gateway behind them could be uniquely characteristic too.