United Church of Canada

I believe that my Grandfather, Reverend William Richard Johnston, born in Horton Township, near Renfrew, Ontario, was one of the earlier Moderators of the united church of Canada.
His name, however, was not listed in the one list I was able to obtain.
He was originally a Methodist. He ministered in churches in Angus and Hudson, Quebec as well as Spencerville and Carp in Ontario.

I would like to trace his career and to know if any of his writings are on file anywhere.
He was married to Emily Maude(nee)Armstrong of Manotick, Ontario. My mother Beatrice Maude Johnston(Thomas) was his eldest and was herself very active in the Church.

any information you could give me would be most appreciated.

maryjbetts@rogers.com