Greathead arrived in Melbourne on the Diana in 1853, accompanied by his wife and four of his children. As a trained chemist, he acted as the ship’s surgeon on the voyage. In the mid 1850s Greathead worked for the Melbourne City Mission as a missionary in Collingwood.  The Mission was established in 1854 by Mrs Hester Hornbrook and Dr John Singleton as an interdenominational mission to the poor. Greathead’s Journal of the Collingwood Flat District for the City of Melbourne Missionary Society, 2 Oct 1854-29 June 1856 gives a detailed account of his work and includes statistical reports to the committee. The journal revealed among other information how few children were attending either day school or Sunday school, which inspired Mrs Hornbrook to establish Ragged Schools for children who due to poverty were unable to attend ordinary schools. It also revealed Greathead as vehemently anti-Irish and anti-Catholic.

Greathead met local schoolteachers and clergymen as he made efforts to get free admission for poor children. After finishing his work as a missionary, Greathead and his wife Sarah worked for a term as schoolmaster and schoolmistress at the Wesleyan Denominational School in Charles Street Abbotsford. By 1860 the Greatheads were active in the work of the Female Refuge in South Yarra, where Mrs Greathead was Matron. In the 1860s Greathead then returned to pharmacy, first renting a shop in Hoddle Street between Vere and Perry streets around 1863, then crossing the road to the northeast corner of Hoddle and Vere streets. Here despite his advanced years he worked until his death in 1877 and continued in his concern for those in straitened circumstances. He died poor, with a net worth of £48.2.0, having already borrowed against his life insurance. His belongings included ‘a few articles of household furniture, very old’ valued at £15, and his chemist's stock in trade valued at £62.10.0. The shop continued as a chemist for many more years, re-built for Henry Jacobs in 1904, and is now 160 Hoddle Street.

Greathead and his shop c. 1868

The Argus; Cummings, Bitter roots, sweet fruit; Journals and papers (SLV MS 9851) (SLV MS 7735); VPRS 59/P0 and P1.