Wallis was born in Devon. He was a fisherman and later a scrap-metal merchant in St. Ives. After the death of his wife in 1922, he turned to painting and known for his port landscapes and shipping scenes painted in a naïve style. Having no artistic training, he began painting at the age of 70, using household paint on scraps of cardboard. He was admired by Ben Nicholson and Christopher Wood, who came across his work when visiting St Ives in 1928 and included it in the Seven & Five Society's exhibition of 1929. He died in Madron Poorhouse.