Grenadiers' Memorial Mural was painted by Frank H. Johnson, one of Canada's Group of Seven artists. It was erected by the church, unveiled by Major General H.D.B. Ketchen CB, CMG, on June 8, 1924, and dedicated to The Winnipeg Grenadiers who died in the Great War. The mural depicts the risen Christ blessing two kneeling members of The Winnipeg Grenadiers.
In the First World War, 281 men from St. Luke’s enlisted for active service, 43 of whom were killed in action. The mural was restored in 2004.