By the end of the 20th century, the firm had grown into a national concern, with 35 shops in Scotland and England, but it went into voluntary administration in 2002 with debts of £5 million.

He was a noted hymnologist and amassed a collection of some 2,500 hymn books and works of hymnic literature.

[1] At the age of 11, he became apprenticed to James McIntosh, a bookseller at 5 North College Street, Edinburgh.

Although he was entitled to a break of one hour at midday, his employer arranged for his lunch to be brought to the shop so that James could remain at his post throughout the day.

He thus became acquainted with some of the leading names in the Scottish publishing industry, including A & C Black, W. R. Chambers, and Thomas Nelson.

[4] Trade was slow at first, but improved over the next few years, thanks in part to the shop's location close to Edinburgh University.

Two years later the firm further expanded into an adjacent shop at 55 South Bridge (the premises previously occupied by Mr. Rickard).

An opening was built into the back wall of this shop to give access to the Infirmary Street premises.

Trade continued to improve and Thin was soon advertising the business as "the largest retail bookselling establishment in Edinburgh".

Having finished his apprenticeship that year, he started teaching religious instruction in evening classes at the church's mission in Cowan's Close.

He then took charge of the senior female class at the Christian Instruction Society, which met at the Old Session House in Bristo.

In 1870, he purchased a plot of land in Stow in the Scottish Borders, on which he had a family house built.

[10] In later life, Thin lived at 22 Lauder Road in The Grange, Edinburgh, where he died in 1915 aged 91.

[2] In 1917, he was reported missing in action,[12] but was in fact taken prisoner and spent the rest of the war in a German POW camp.