Born in 1844 in St. John, New Brunswick, William Harrison Tilley was the son of Sir Samuel Leonard Tilley, one of the Fathers of Confederation. After studying mathematics and the natural sciences, he graduated from the University of New Brunswick in 1864. He then studied divinity at King's College in Windsor, Nova Scotia and was ordained priest in 1868. Tilley came to London initially as a curate at St. Paul�s Cathedral. He established a mission in the then east end of the city, conducting services in a house on Adelaide Street. In 1873 Tilley was appointed the first rector of the newly built Memorial Church (now Bishop Cronyn Memorial Church). Four years later he took the position of Assistant Minister at St. James Cathedral in Toronto. He died after spending only four or five months in Toronto. His funeral service was held at Cronyn.

Tilley's character might be summed up in a description given of him by a fellow priest:

To meet Mr. Tilley was like meeting a fresh breeze on a sultry day, or like feeling the welcome hearth-glow on a cold day.

The warmth of his character had one or two unexpected effects on his some of his parishioners. One woman, after seeing him preach from the pulpit, thought that he was almost an angel in his white surplice.

Tilley was involved in many evangelical endeavours, but his favourite was the Sunday school. Such was the affection of its members to him that they presented to the church a baptismal font in his memory. The font now stands at the entrance to the south transept of the church. Stemming from his church missionary activities, Tilley came to admire Josiah Henson, the person on whom the main character in Harriet Beecher Stowe's Uncle Tom's Cabin was based. Out of this admiration and without ever meeting Henson, in 1876 Tilley wrote a letter of introduction for Henson to the Colonial and Continental Church Society in England .

After his death, Tilley's family moved back to London and were members of the parish for many years. Parishioners bought a house on King Street for the family to live in. Elizabeth Tilley, his widow who taught music for a living, was deeply involved in missionary work. A plaque under the gallery in the church acknowledges her as one of the three founders (two others were Cronyn parishioners) of the Woman's Auxiliary to the Missionary Society of the Church of England in Canada .