Morris was born in Sketty, Swansea, the son of George Lockwood Morris, ironfounder and Welsh rugby international, and his wife Wilhelmina Cory. He was educated at St Cyprian's School Eastbourne and Charterhouse.

He failed the exams to enter the army as an officer and at the age of 17 set out on a steamship to Ontario, Canada, to work on a farm. After a succession of jobs, including as a dishwasher and bell boy in New York, he returned to Wales and entered the Royal College of Music to study singing. He gave up singing for painting and went to Paris where he trained briefly at the Academie Delacluse in Montparnasse before the interruption of World War I.

He joined the Artists Rifles, but failed a medical examination before embarking for France as a result of a failed operation in childhood. As he was an experienced horseman, he was allocated to training Remounts at Lord Rosslyn's stables at Theale, Berkshire. He worked in the company of Alfred Munnings, under Cecil Aldin. He was discharged when the army took over the Remounts in 1917.

Morris went to Zennor in Cornwall where he studied plants and painted water colours. There he became friendly with Frances Hodgkins whose portrait he painted. He was in London at the time of the Armistice in November 1918 when he met Arthur Lett-Haines with whom he began a life-time relationship, and shortly after moved in with Haines and his wife. The trio planned to go to America, but in the event Aimee Lett-Haines left on her own and the two men moved to Cornwall. They converted a row of cottages at Newlyn into a larger house and stayed there until the end of 1920 when they moved to Paris.^[2]

Paris was their base for the next five years, when they travelled extensively in Europe. Morris also studied at the Academies Moderne and La Grande Chaumiere. Morris had successful exhibitions in London in 1924 and 1926 and later in that year they settled back in England.^[3]

After staying with his sister Nancy Morris in Corfe Morris and Haines found a studio in Great Ormond Street which they moved into in 1927. Morris became a member of the London Artists Association and the Seven and Five Society for which he was proposed by Winifred Nicholson and seconded by Ben Nicholson. He was especially friendly with Christopher Wood and renewed friendship with Frances Hodgkins. At the end of the 1920s Morris became involved with much commercial work designing textiles for Cresta Silks with Paul Nash and posters for Shell and B. P.