Elphinstone Walker was christened 26 January 1781 in Colinton, Midlothian, Scotland, son of Marion Miller and Robert Walker. His brothers and sisters included Isobel, Marion, Margaret, Robert, Thomas, Adam and James.
In 1801 he was employed as surgeon on the convict ship Atlas, Captain Richard Brooks.
The Atlas departed Ireland on 29 November 1801 and arrived in Port Jackson on 7th July 1802.
Elphinstone was employed as Surgeon on Euphrates in 1803 - 1804.
The Euphrates under Captain George Welstead, was engaged in the south seas and returned to England early in September 1803, departing in convoy for the Bengal on 27th September 1803. She was the last of the convoy to depart. Passengers who sailed on her included Lady Rodney and children, two Miss Pauls (Governesses), Mr. Scott jun., of Bengal and Mr. John Thomas Roberdeau of Portsea, writer for the Bengal.
Later a letter was published from a young man of the Bengal Civil Establishment, a passenger on the Euphrates, bestowing praise on the unremitted attention and vigilance of the indefatigable officer Capt. Lock of the Revoutionaire, in convoying the fleet. The fleet had survived the storm and water spout which desolated Madeira on 10th October 1803 which Island they saw on the 11th. Information was received that the Euphrates had, in company with a Privateer taken on the coast of Africa, a valuable prize laden with guns and gold dust. It was reported that she had still not arrived at Bengal in July and August 1804.
Another vessel the Admiral Aplin had sailed a month earlier on 28th August 1803 and been captured by the French privateer La Psyche on 9th January 1804 and fears were held for the safety of the Euphrates. She arrived finally at Madras on 20th February 1804 and from Madras for Bengal on 16th March under convoy of His Majesty's sloop Victor. She was reported to have arrived at Bengal early in April 1804 and sustained some damage by getting aground while going up the river.
No mention can be found of Elphinstone Walker, however another man Henry Kennedy of Belfast died of bilious fever on the Euphrates in August 1804.
Elphinstone Walker died in August 1804 at Bengal. In an application for probate in 1812 by an attorney William Walker acting on behalf of Elphinstone's father Robert Walker, Elphinstone Walker is described as a surgeon belonging to the East Indian Merchant Ship Euphrates. He was a bachelor and his estate was to pass to his father. 
2). The Euphrates sailed in company with the Earl Spencer, the Lord Melville, the David Scott and the Britannia from Fort St. George on 21st October 1804 and from St. Helena 31st December and departed St. Helena on 13th January, arriving back in Plymouth on 10th March 1805.