Moutray was baptised in Yorktown, Virginia in 1752. Her parents were Catherine Selby and Lieutenant John Pemble of HMS Tryton.[1]
She married on 2 September 1771 to a naval officer, John Moutray at Berwick upon Tweed.[1] Her husband was thirty years older than her.[2] She and John had twins in 1773 that they called Catherine and John.[1]
In the 1780s they were in Antigua where her husband was the Royal Commissioner.[2] one of the captains there was Horatio Nelson who hated this particular posting. The only thing in his mind that made it bearable was the presence of Mary Moutray.[2] Mary and her husband were only there for a few months in 1784 but she made a lasting impression on Nelson. He first met her in June 1784 and the friendship developed despite Nelson reporting her husband for a breach of procedure.[3] Nelson said that he cried when he first thought of Antigua without her. He said that her company was where he had "spent more happy hours than anywhere else".[2] When Nelson did start to court a wife he would tell, Frances Nisbet, about Mrs Moutray.[1] Mary wrote about Nelson noting that he took to wearing a wig because he had lost hair dues to a fever. Cuthbert Collingwood kept a sketch of him in that wig.[4]
After John Moutray died Mary petitioned for a pension and although she gained Royal support the request was denied by Lord Howe on the grounds that it might create a precedent for other claims. Some commentators have supposed that if John Moutray had died in Antigua then Nelson would have married Mary.[1] Nelson took an interest in Mary's son John. He was with Nelson at the Siege of Calvi. When John died during the siege Nelson paid for his memorial.[1]
When Nelson died in 1805 then Cuthbert Collingwood wrote to her. He too had been captivated by her when he was in Antigua and he had written poetry about her.[2]
John and Mary's daughter Katherine (aka Kate) married the Thomas de Lacy who was a long-serving archdeacon of Meath in 1806. Mary died in Meath in 1844.[1]