Thanks for that - he was born in 1874, so would have been about 14 at the time. There are other newspaper references to him winning prizes around the same time.
His father Thomas Minford Millar died in 1893 while living at 'Clonoriel' in Belmont, Belfast, but by 1899 Samuel and his three brothers were living at 151 University Street Belfast, as indicated on the attestation form. I wonder what persuaded him to join the RAMC in 1899; having been kicked out for drunk on duty, he rejoined in 1915 and went to France in October with the 36th Ulster Division, again in the RAMC, but by March 1916 (i.e. before the Somme) he had been invalided to the Western Military Hospital in Newport, Wales, where he died from TB in March 1916 aged 42 (relatively old I'm sure, compared to his compatriots). There was no conscription in Ireland, so he would have been a volunteer - unfortunately his WW1 service record is missing.