Lleist was an early 20th century Sydney and London painter, cartoonist, war artist and teacher. He was an inaugural council member of the Sydney Society of Artists in 1895 and after the merger (1902-07), a member of the Royal Art Society of NSW. He also trained as a furniture designer working for David Jones and Co., Sydney and painted murals for the Martin Place nightclub Romano's.
1877 according to Greenwall; 1878 according to Christie's Australia. His date of birth (21st August 1873) is confirmed by his attestation form completed by him on joining the AIF in 1917.