James Brydone was born in 1779 in Selkirk, Scotland. He married Elizabeth Hislop, daughter of Alexander Hislop Esq., of Knightsbridge, on 11th June 1818 at Marylebone New Church. 
He was included in the Navy List of Medical Officers of 1814.
James Brydone was employed as Surgeon Superintendent on the convict ship Eliza in 1820. The Sydney Gazette reported the arrival of the Eliza in Port Jackson-
Captain Hunt, with 160 male prisoners, one having died on the passage. The Surgeon Superintendent Dr. Bryden of the Royal Navy, whose care it will be perceived, by the loss of only one person must, with that of the Captain and Officers, have been as diligent as exemplary, and entitled to our best thanks. She sailed from England on the 15th October, and touched nowhere
James Brydone remained in New South Wales for some months and became President of a Medical Board assembled by Governor Macquarie to enquire into the state of disease in the Colony. He departed on the Tuscan in August 1820. John Morgan, surgeon superintendent of the Mary in 1819 returned to England under the care of Brydone having become ill while in the colony
By 1851 John Brydone resided at Petworth Sussex - On the 1st inst. at Spalding, by the Rev. William Moore, D.D., Walter Marr Brydone, Esq., son of James Marr Brydone Esq., Royal Navy, of Petworth Sussex to Hannah Maria, daughter of Thoms Smith, Esq., of Spalding 
He died at Petworth in 1866 - On the 29th Ult, at Petworth Sussex in his 87th year, James Marr Brydone, Esq., retired Staff Surgeon R.N., 
At Petworth, Sussex, aged 86, James Marr Brydome, esq., Retired Staff Surgeon, R.N. He was born at Selkirk, N.B., in 1779, and was the schoolfellow and intimate friend of Admiral Sir Charles Malcolm, and also of Mungo Park, the illustrious African traveller. He was educated for the medical profession, at Edinburgh University, and became assistant-surgeon to Adam Park (brother of Mungo), on board the Calcutta, East Indiaman. The surgeon having died on board a king's' ship, which was 'spoken with ' on a voyage, Brydone was taken, molens volens, to fill the place, and it was thus that he entered the Royal Navy, in 1804.
He caught the yellow fever at Calcutta, owing entirely to the captain insisting upon coiling a rope unwashed from the mud of the Hooglie in the hold of the ship, and he was invalided home. This was the only illness from which he suffered until within a fortnight of his death. He was assistant-surgeon of the Thunderer at the Battle of Trafalgar, and often stated that, at dawn, on the 21st Oct., 1805, he was the man who, without the aid of glass, pointed out to the signal. officer the position of the French fleet; and that the signal to that effect was made from the Thunderer, about three minutes before it was hoisted on board Nelson's flag-ship, the Victory. He was at the siege of Gaeta, and at the action at the Isle of Anholt, and received the Trafalgar medal and clasps for these services. He was one of the last of the “Trafalgars.” He was in charge of a convict ship to Aus. tralia, and afterwards he served under Admiral Sir James Gordon in the Active fri. gate, which attended King George IV. to Ireland, in 1821. He was an excellent swimmer, and on a voyage in the West Indies plunged from the stern-cabin winglow of the Conquestador, and saved the life of a sailor, for which he received the thanks of the society and of the Admiralty.
He was assistant staff surgeon at Portsmouth dock-yard, and held the same position at Deptford; he was afterwards staff-surgeon of the Royal Victoria yards, at Deptford. In 1834 he retired from the navy, and went four times to Canada, for the Earl of Egremont, in charge of settlers from Sussex. In 1838 he came to reside at Petworth, and in 1847 he became land steward to the Lord Leconfield, an office which he filled to the time of his decease. The ancestors of the deceased had lived for many generations at Selkirk, and, in 1513, William Brydone, the town clerk, led out 100 volunteers to the Battle of Flodden. He was knighted on the field of battle, and the basket-hilted sword which he used on that occasion is still in the possession of the family. -Surrey Standard
.- Gentleman's Magazine