Dr. A. T. Barr was born in Fife, Scotland, and received his early education in the schools of Clydebank, from which he matriculated into Glasgow University in 1908. Before completing the course for his degree, he emigrated to Canada in 1911. While working in the Western Mission Fields, be continued his studies, and in 1914 received his B.A. from the University of Saskatchewan. After theological courses at Robertson Presbyterian College, Edmonton, be graduated with a B.D. degree from the University of Alberta in 1917. Following ordination in April of that year, be served as pastor at Lacombe Alberta, until 1921. Having been awarded a Maclean travelling scholarship, he began post-graduate work at Hartford Conn. and in 1924 attained the degree of Ph.D.
In 1925 Dr. Barr was called to Central Presbyterian Church, Brantford, from which, after a successful pastorate, he came to St. Paul's in December 1931.
His ten years in Peterborough during the great depression were both productive and tempestuous. A highlight of his tenure was as host minister to the 59th convocation of the General Assembly of the Presbyterian Church of Canada at St. Paul's. The Water St. manse was considered more than adequate for Dr. Barr and family, as there were four children. The eldest son Ferguson, elected to follow his father's footsteps, and was himself a minister of the Presbyterian Church.
In 1941, Dr. Barr accepted a call to St. Andrew's Presbyterian Church in St. John’s Newfoundland, and later moved to the Sutton West charge in Ontario. On two occasions of dedications of memorial windows he visited St. Paul's, and was also present at the opening ceremonies of the new Christian Education Centre in 1959. Dr. Barr passed to his reward in June 1961, and the demise of Mrs. Barr, occurred a short four months later. They are both buried in Little Lake Cemetery.