John McGlashan was born in Edinburgh, Scotland, on 7 November 1802, the son of John McGlashan, a furniture dealer, and his wife, Mary Fraser. John attended Edinburgh High School and the University of Edinburgh, qualifying as a solicitor on 10 September 1824.
On 16 January 1827 McGlashan married Isabella McEwan, whose surname was sometimes spelt McEwen, at Stirling; there were six daughters and four sons of the marriage. On 7 July 1830 he became a member of the Faculty of Admiralty Procurators, and from 1831 to 1853 was a commissioner for proofs in the Sheriff's Court. Although deafness incapacitated him for work in the courts, he established his reputation by numerous writings on legal subjects.
In addition to his legal work McGlashan was a dedicated and well-read churchman, with strongly evangelical convictions which led him out into the Free Church in 1843 as a member of Free Greyfriars. 'All our ideas take their texture and colour from our religious belief, all institutions, all moral restraints, all laws, are the offspring of our religion'.
Because of his rejection of an established church and because he believed that the church should embrace the whole community, McGlashan became interested in the proposal for settlement in Otago. He saw in it the possibility of a finer Scotland, embodying the best British and Christian values. Appointed secretary of the Otago Association at £300 a year in 1847, he worked compulsively, if not always effectively, for the success of the colony. He oversaw the arrangements for the dispatch of 12 of the first 14 ships, and edited the Otago Journal from January 1848 to August 1852, setting out the advantages of emigration but saying little about the hardships. He lobbied the Colonial Office vigorously, but with only partial success, to safeguard the interests of Otago in the proposed constitution. Clause 78 of the Constitution Act 1852, designed to provide this safeguard, was substantially his work.
In 1853, now 50 years of age, McGlashan himself became an emigrant. With his family he sailed for Dunedin (where his younger brother Edward was already established in business) on the Rajah, arriving in October to be welcomed at a public dinner. Through emigration he was seeking wider opportunities for himself, and hoping to realise in the new land his vision of a fully Christian society. He speedily became one of the leading figures in Otago, active in a variety of organisations and public offices. Some of the complaints about his tardiness and ineptitude in administration may well have stemmed from over-involvement. By January 1854 he had been appointed provincial treasurer and solicitor.
Politics became an important avenue. He decided to stand for election to the provincial council, rather than the geographically remote House of Representatives in Auckland. He was a member for the Western District from 1855 to 1863. From 1855 to 1861 he served as provincial secretary and provincial solicitor. In 1858 he became deputy superintendent, but his closeness to Macandrew and his own administrative limitations led to an uncomfortable scrutiny of his part in Macandrew's murky financial dealings. McGlashan was exonerated, but he had been careless. His political career suggests a lack of judgement, an inability to see other points of view and a capacity to confuse trivia with more important issues, which led to his fighting for both with equal obduracy.
McGlashan's legal experience, however, continued to be important to the province and he was codifying its ordinances when he died. He was also involved in land law and unsuccessfully fought the colonial government over the ownership of New Zealand Company and Otago Settlement lands, arguing that they could not lawfully be included in Crown lands. The Warden's Court Rules were also his work. In 1862 he became registrar of deeds.
His work for the Presbyterian church was also very important. In 1847 he drew up The institutes of the Free Church of Otago; after his arrival he became an elder of First Church, Dunedin, and worked very closely with the Reverend Thomas Burns. He was the first clerk and procurator of the presbytery set up in 1854, and drew up the Model Trust Deed in 1857, as well as helping to establish the sustentation fund for ministerial stipends. Although he was ridiculed in 1857 for suggesting a fund for the building of a noble church in Dunedin, the present First Church is a result of his vision. McGlashan had both a visionary and a realistic understanding of the relationship between church and society. 'The surest foundations of a people's lasting prosperity are those which are laid in the profound reverence of God and devout observance of his public worship – being persuaded likewise that it is incumbent upon them to prefer God's honour before their ease and satisfaction'.
Nevertheless McGlashan's studies of history convinced him that not everyone subscribed to that opinion. He believed that it was essential to have the church endowed sufficiently to protect it against opposition and carelessness, but without removing the need for Christian liberality. Hence he campaigned for a proportion of the proceeds of land sales to be set aside for religion and education.
Otago owes a good deal to McGlashan's conviction that education would promote equality. He wanted a school in every parish, with a highly educated and well-paid master. Above that elementary system he wanted the equivalent of the Scottish burgh schools. Elected to the Otago Education Board in 1856, he was its first secretary and used his delegated authority to the limit in order to further his aims. W. H. Cutten strongly opposed McGlashan on the close link between church and school, but Otago's superior education system owed much to McGlashan.
His lectures on 'Civilisation and Christianity' (1854) and 'Colonisation' (1857) set out a number of assumptions, which help to explain the priorities of the Free Church leaders of Otago. While he was not a figure of national importance, McGlashan's public-spiritedness and energetic participation in religious, educational, civic and provincial affairs made a significant contribution to Otago.
John McGlashan died in Dunedin on 2 November 1864, as the result of a riding accident. John McGlashan College, founded in 1918 after his daughters' gift of the family home and estate, commemorates him.