On her maiden voyage to Bombay in October and November 1935, Strathmore gained the Blue Riband for the route from the Mediterranean to India.
In April 1936 she took the new Viceroy of India, the Marquess of Linlithgow, to Bombay with his wife, daughters, and personal staff, and brought home his predecessor, the Marquess of Willingdon.
Later in 1936 she took a British-American climbing expedition, including Bill Tilman, Noel Odell, and Charles Snead Houston, to India for the successful first ascent of Nanda Devi.
In 1938 the ship brought the Australian cricket team, including Don Bradman, to England for the 1938 Ashes series.
Other notable passengers in the ship's early years included the writer W. Somerset Maugham.

In August 1939, Strathmore set off on a three-week cruise to the eastern Mediterranean, but shortly after she had passed Gibraltar there came an Admiralty signal ordering non-essential British ships to get out of the Mediterranean.
The cruise was diverted to Rabat and from there it was intended to proceed to Bermuda, but after only one day at sea there came a signal that war was imminent, and the ship returned to Tilbury, with a blackout being imposed after dark.
 On 31 March 1940, towards the end of the "Phoney War", the vessel was requisitioned on the orders of the Ministry of Shipping, which later became the Ministry of War Transport, and during the rest of the Second World War she served as a troop ship, with no major incidents in that role.
On 21 July 1941 Strathmore sailed from Newfoundland carrying 3,800 Canadian soldiers to Britain.
In February 1947 she sailed from Southampton bound for Singapore, Hong Kong, and Shanghai, carrying some 2,000 people going to China, including missionaries, colonial police, business men, and their families, many returning home after being displaced by the war.

On 15 May 1948 Strathmore was returned to P&O and in 1948–49 was refitted at Vickers-Armstrong.
In October 1949 she again entered service between London and Australia, now with berths for 497 first class passengers and 487 in tourist class.
During this period Felicity Kendal travelled to India on the ship, as a small child.
She later remembered that "When I was a few months old, Mary was picked to be my ayah from groups of servants lined up on the quayside in Bombay Harbour, waiting to be chosen by the hurrah sahibs and memsahibs as they disembarked from the S.S. Strathmore".
On 1 May 1952 the ship, suffering from engine trouble, arrived two days late into Sydney harbour, with the result that 49 angry passengers for New Zealand missed their connection, the Wanganella, which went past Strathmore in the harbour.

In 1954 the ship was again refitted, this time as a single-class ship with 1200 berths, for P&O's migrant and tourist business.
In the late 1950s and early 1960s she was sometimes used for short holiday cruises out of London, in between sailings to Australia.
In October 1956, while in the Thames estuary, she hit a Norwegian merchant ship, Baalbeck, with some minor damage.
On her maiden voyage to Bombay in October and November 1935, Strathmore gained the Blue Riband for the route from the Mediterranean to India. In April 1936 she took the new Viceroy of India, the Marquess of Linlithgow, to Bombay with his wife, daughters, and personal staff, and brought home his predecessor, the Marquess of Willingdon. Later in 1936 she took a British-American climbing expedition, including Bill Tilman, Noel Odell, and Charles Snead Houston, to India for the successful first ascent of Nanda Devi. In 1938 the ship brought the Australian cricket team, including Don Bradman, to England for the 1938 Ashes series. Other notable passengers in the ship's early years included the writer W. Somerset Maugham.
In August 1939, Strathmore set off on a three-week cruise to the eastern Mediterranean, but shortly after she had passed Gibraltar there came an Admiralty signal ordering non-essential British ships to get out of the Mediterranean. The cruise was diverted to Rabat and from there it was intended to proceed to Bermuda, but after only one day at sea there came a signal that war was imminent, and the ship returned to Tilbury, with a blackout being imposed after dark.  On 31 March 1940, towards the end of the "Phoney War", the vessel was requisitioned on the orders of the Ministry of Shipping, which later became the Ministry of War Transport, and during the rest of the Second World War she served as a troop ship, with no major incidents in that role. On 21 July 1941 Strathmore sailed from Newfoundland carrying 3,800 Canadian soldiers to Britain. In February 1947 she sailed from Southampton bound for Singapore, Hong Kong, and Shanghai, carrying some 2,000 people going to China, including missionaries, colonial police, business men, and their families, many returning home after being displaced by the war.
On 15 May 1948 Strathmore was returned to P&O and in 1948–49 was refitted at Vickers-Armstrong. In October 1949 she again entered service between London and Australia, now with berths for 497 first class passengers and 487 in tourist class. During this period Felicity Kendal travelled to India on the ship, as a small child. She later remembered that "When I was a few months old, Mary was picked to be my ayah from groups of servants lined up on the quayside in Bombay Harbour, waiting to be chosen by the hurrah sahibs and memsahibs as they disembarked from the S.S. Strathmore". On 1 May 1952 the ship, suffering from engine trouble, arrived two days late into Sydney harbour, with the result that 49 angry passengers for New Zealand missed their connection, the Wanganella, which went past Strathmore in the harbour.
In 1954 the ship was again refitted, this time as a single-class ship with 1200 berths, for P&O's migrant and tourist business. In the late 1950s and early 1960s she was sometimes used for short holiday cruises out of London, in between sailings to Australia. In October 1956, while in the Thames estuary, she hit a Norwegian merchant ship, Baalbeck, with some minor damage.
RMS Strathmore