[1] When John Gwynn was only ten years old his mother Mary Stevenson was drowned, together with her maid, while bathing off the rocks on the Londonderry coast.

His father's diary (still preserved at Trinity) records John's success in the entrance examinations, in the winter of 1845: November 12 ... After considerable delay, we received the announcement, viz.

John at the head of all the candidates from all the schools, his numbers being 25 ahead of the second best man.Four years later, as an undergraduate, John Gwynn stood outside Trinity College and watched William Smith O'Brien and other political prisoners being marched through the streets of Dublin on their way to Kingstown (Dún Laoghaire), where a convict ship was waiting to transport them to Van Diemen's Land (Tasmania).

[4] The two sons of Anthony Trollope, the novelist, were admitted to St Columba's in 1858, but were withdrawn the following year after John Gwynn had sent one of them home in disgrace, accused of a serious misdemeanour.

His greatest work, which took him twenty years to complete, was a landmark annotated edition of a ninth century Irish manuscript written in Latin and known as the Book of Armagh.

[8] These were later added to the Gospels and Epistles of Philip E. Pusey and George Gwilliam to produce the 1905 United Bible Societies standard edition of the Syriac Peshitta.

Their elder daughter, Lucy Penelope Gwynn (1865–1947), made a notable contribution to the cause of women's education when she was appointed the first Lady Registrar at Trinity College.

[10] Stephen Lucius Gwynn (1864–1950), the eldest and most famous of the sons, was an MP, a prominent Irish patriot and a prolific writer.

May, with her children, entered the Roman Catholic church while in her thirties, and her second son Aubrey Osborn Gwynn SJ later became a Jesuit priest.