Fr. Cleary was appointed to the Port Hope parish January 6, 1955, and served as pastor at Our Lady of Mercy for over 20 years during which time he saw his parish grow to over 400 families.  He served as padre to the Royal Canadian Legion Br.30, Port Hope.  A former teacher, he was dedicated to the establishment of the separate school system in the area. As well, he was a member of the Port Hope Ministerial Association.

     During his time in Port Hope as pastor of Our Lady of Mercy, he initiated a program of Catholic education. The first step was the building of a school of four rooms in 1956 to accommodate one hundred and forty pupils. The Sisters of St. Joseph were invited to take charge of the operation of the school and Sister Alma (Geraldine Harrington) was appointed first Principal of St. Mary's Elementary School.  The first convent for the Sisters was a frame house on Walton St.  Later this was sold and the convent was transferred to the present brick residence across from the church. During the first year of the school's operation two class-rooms were added and in 1957 a seventh class-room was opened.  In the following year two new schools were built in the rural areas of the parish, St. Teresa's at Sion and St. John Bosco's in Osaca. 

     In 1960 a second school was commenced in Port Hope (St. Anthony's), a senior school for Grades Seven, Eight, Nine and Ten.  Through the instrumentality of Fr. Cleary, Separate School Sections were organized at Welcome, Morrish and Elizabethville and thus enabled the boards thereof to secure grants and transportation for children to establish Separate Schools.  As a result, St. Mary's School in Port Hope had to be enlarged, this addition included two class-rooms and a combined auditorium and gymnasium.  Fr. Cleary himself has been known for driving the kids to and from school himself for a time.

     Fr. Cleary was elected Dean of the Counties of Durham and Northumberland for a five year term in 1969. In recognition of his long and fruitful service to the church he was named an Honorary Chaplain of the Papal Household with the title of Monsignor in April, 1972. Father Leo Cleary was instrumental in the formation and is a founding member of the Knights of Columbus, Port Hope Council 6490, chartered on May 7, 1973. 

     Monsignor Leo Anthony Cleary, a much loved figure among Catholics and non-Catholics alike, died December 20, 1997 at the age of 99.

Sources:

     From The Pioneers To The Seventies, by Edgar J. Boland, May, 1976

     Cobourg Daily Star, Saturday June 20, 1998