Dugald Buchanan became a noted evangelist in his native Perthshire some years following his prolonged period of spiritual awakening, during which time he attended services connected with the Cambuslang revival of 1742. For many years a schoolmaster at Drumcastle near Fortingal, Buchanan was appointed a teacher with the SSPCK in 1753. Prosecuting unofficial evangelistic labours with the same care and zeal to which he continued to oversee his school, Buchanan earnestly sought to inculcate godly standards among the spiritually impoverished inhabitants of Rannoch. Within a year Sabbath pastimes such as football and drinking were entirely abandoned, and such an interest awakened in divine things that the schoolhouse of Drumcastle could not contain all who came to hear the Word of God.
In goof weather hundreds met on the banks of the rivers Tummel or Rannoch to hear Buchanan preach. His services were attended by remarkable power and a deep and widespread revival resulted, characterised by the conversion of souls, numbers of whom traversed considerable distances to attend his meetings.
Noting such desired outcome, the Dunkeld Presbytery of the Church of Scotland formally invested Buchanan with the functions of catechist and evangelist in 1755.
Jealous of his success and alarmed by his assuming ministerial authority (he did more of the work of pastor there than the ministers appointed to the parish), some clergymen complained that Buchanan's public teachings were of a wild inflammatory character, fitted to fanaticise rather than to edify. Still, the good work went on, lives being transformed by the catechist's earnest and generally tender appeals. The power attending his preaching is evidenced by a memorable service held at the head of Loch Rannoch. A bitter feud had arisen between the people of two adjacent townships of this district, who normally refused to come anywhere near each other. Both groups, however, agreed to hear Buchanan preach, albeit from different sides of a stream, in the middle of which, perched on a large stone, the evangelist addressed his audience. So powerful was the message that both sides were deeply and visibly affected. Confessing their faults mutually, these former enemies parted that day as friends.
'Reminiscences of the Life and Labours of Dugeld Buchanan', by Rev A Sinclair, 1875, pages 51-4. Summarised by Tom Lennie in 'Land of Many Revivals', 2015, pages 149-50.