On graduating M.A., with first class honours, in 1898, he was appointed Assistant Master at Dundee High School. In 1902 he was promoted to be Head of the Department, and he served in this capacity until his retirement in 1938; soon after this he was elected a Member of the Board of Directors.
As a teacher he was supreme. Sir Edmund Whittaker once told the present writer that he was the best teacher of Mathematics in the East of Scotland. If there were any doubts as to his rapid promotion to the headship after only four years of teaching, these were soon dispelled, for three years later there began an almost unbroken sequence of highly-placed John Welsh Mathematical Bursars at his old University. His outstanding success as a teacher depended on three things - (1) he was a first-class mathematician with a great love for his subject; (2) he prepared every lesson with meticulous care; (3) he was a strict disciplinarian.
His teaching was most intensive and there was never a moment of relaxation in any of his classes. No class was ever late in assembling, for awaiting them on the blackboard would be three examples headed "Just Now" and the tawse for anyone who had not submitted one correct example within ten minutes. If he was a "terror," he was a most genial human terror, for those at the top had continually to justify their place, while those at the bottom had only to fear the tawse for a really abysmal lack of knowledge.
Too busy with his teaching to produce original work, he kept his mind sharp by reading new books on advanced mathematics. New methods were all carefully kept in a series of notebooks for use in his class-work. The present writer well remembers being taught the simpler inequalities from Hardy, Littlewood and Polya and, on later seeing a copy of this book, finding that it had just been published.
Mr Meiklejohn was a keen swimmer all his life, and a month of every summer was spent in exploring some new part of the Highlands and Islands, either on foot or on cycle. To the very end, he kept in touch with most of his senior pupils, all of whom had come to realise that, though at times it may have been hard and strenuous, they had all been through a great formative experience. Having discovered his own mathematical talent late, he devoted his life to ensuring that any in his pupils was soon discovered and then nurtured with every ounce of his ability.