Macallan held the Bachelor of Laws degree, recorded as B.L. Scotland has a legal system distinct from England's, and its professional training and admission of lawyers developed within that separate tradition.
The College of Justice, established in 1532 by James V, included the Writers to the Signet and laid foundations for Scotland's legal system. This institutional framework shaped the role of Scottish solicitors for centuries before Macallan's admission to practice in 1951.
Harry Macallan worked in Glasgow as a partner of Maclay Murray & Spens, a firm whose roots reached back to the late nineteenth century. The practice was founded in Glasgow in 1871 by David Maclay, David Murray and John Spens as the first law firm in Scotland with a specifically commercial practice. Its earlier origins lay in a partnership formed in 1869 by David Murray and George Smith, which later took the name Maclay, Murray and Spens.
The earliest date in Macallan's documented career is his admission to practice in Scotland in 1951. His work at the firm belongs to the period when Glasgow's commercial economy, shaped by its industrial growth, made the city a major centre for business legal services.
In 2017 the firm agreed to combine with Dentons, then the world's largest law firm, which made the Glasgow practice part of a much larger international network.
Macallan's memberships connected him with two long-established Scottish legal bodies. The Royal Faculty of Procurators in Glasgow, incorporated before 1668, serves the legal profession in Glasgow and West Central Scotland and provides members with a law library, continuing education and a venue in the city centre. The Royal title was added in 1950, shortly before his admission to practice.
He was also a Writer to the Signet. The Society of Writers to His Majesty's Signet, founded in 1594 and part of the College of Justice, is a private association of Scottish solicitors whose members are entitled to the postnominal letters WS.
