Alexander Stewart purchased a 250 acre property at Ashgrove in 1875-76 on which he built his home stately home Glen Lyon. The property was bounded by what is now known as Stewart's Road and extended along both sides of Enoggera Creek.
In 1901 just over eight acres on the eastern edge of the Glen Lyon estate was transferred to Jeannie Maxwell Stewart, the wife of John Stewart. Grantully was built soon after. Prior to building this house, Stewart and his family lived at Glen Lyon, and for a few years in a house at Ashgrove named Upotipotpon.
At the time Grantully was built, Ashgrove was a sparsely populated rural community. Despite its close proximity to the city, Ashgrove was relatively slow to develop. The district's earliest extant house was built at St John's Wood around 1865. The following year Waterworks Road was built to provide access to Enoggera reservoir and a few scattered farms and gold diggings were established. By the mid 1870s when construction began on Alexander Stewart's home Glen Lyon, the district was still mostly bush and vacant land. Among the area's first suburban housing estates to be offered for sale was the Holmesbrook Estate (later the Grove Estate) in the late 1870s, but the lack of public transport to the area meant that suburban expansion was slow. By the mid-1880s just 67 residents were recorded in Ashgrove. By the turn of the century, the area was still mostly rural, dominated by dairy farms, market gardens and some scattered houses.
Alexander Stewart emigrated to Brisbane in 1858 and established a small clothing retail business. He later entered into a partnership with his friend William Hemmant, opening a general drapery on Queen Street. The partnership dissolved in 1871 when Hemmant was elected to parliament, although Stewart continued to trade under the name Stewart and Hemmant. In 1898 he opened a clothing factory in Fortitude Valley, one of the first in Queensland devoted entirely to the manufacture of clothing. The company and its products became household names, producing clothing such as moleskin trousers under the Manx label and shirts under the Thistle brand.
Although John Stewart had been working for his father for some time, in 1903 Alexander Stewart's sons formerly entered the business, and the company became known as Alexander Stewart and Sons, a limited liability company with a nominal capital of 140 000. Despite his sons' involvement, Alexander Stewart continued to manage the company almost until his death in 1918.
Like his father, John Stewart held a prominent position in Brisbane society. He was an active and senior member of the Presbyterian church, as an office bearer of St Andrew's congregation, a member of Session, and Chairman of the Assembly's Board of Investment and Finance. He was a longstanding member of the Young Men's Christian Association, and was on the board of Directors and Vice President for several years. He was a Life Member of the Brisbane Cricket Association, and a member of the Brisbane Golf Club and Toowong Bowling Club.
In 1924, the same year in which the Glen Lyon estate was subdivided for housing, Grantully was also put on the market. Over five acres were sold to T. M. Burke, the developer responsible for creating the Glen Lyon Gardens housing estate, and the remaining land, comprising two and a quarter acres, and the house were sold to Thomas Joseph Moore. Moore mortgaged the property in 1924, but the following year sold the house and land to trustees for the Sisters of Charity, a teaching order from Sydney.
On 1st June 1925 St Finbarr's Primary School opened its doors and the five sisters taught 28 pupils on the verandahs of the house. A week later, Catholic Archbishop James Duhig opened and blessed the convent, which occupied the old Stewart house. The school and convent were named in honour of Sister M. Finbarr Sullivan who was the first Sister of Charity to be buried in Queensland.
The school grew rapidly, reflecting the residential growth that occurred in Ashgrove in the 1920s and 1930s. By 1927 there were 175 pupils enrolled. The sisters held frequent fund raising events to help keep the school going, and these were strongly supported by the locals, highlighting the importance of the school to the local community.
The St Finbarr's Parish Church was established in 1927 and the primary school was transferred to classrooms below the timber church building. At this stage the decision was made to introduce secondary classes, and secondary girls took over the verandahs at Grantully. The two acre property was steadily built upon over the ensuing years with additional facilities. In 1934 a kindergarten was opened to cater for the many young families that had moved to the district. In 1941 a new brick secondary school building was completed and the secondary school became known as Mt St Michael's College. Several further additions were made over the following decades.
Grantully still serves as a convent, and is the heart of the school precinct. It was the focus of the School's Diamond Jubilee celebrations in 1985, serving as a stage for entertainment, with audiences gathered on the lawn in front of the house. The Sisters of Charity Education Council still conducts the College, but their charge over the Primary School ended in 1981.