[2] She purchased two town sections on Oxford Terrace and opened Christchurch Ladies' School on 22 March 1854 in a building called Avon House.
Between 1858 and 1860 Thomson bought four more town sections in Salisbury Street and Park Terrace, and in 1862 built a large house on land in Papanui Road which served as both the school premises and her home.
[2] While in England, Thomson wrote and published a book on her travels and life in New Zealand, titled Twelve Years in Canterbury.
Her will, which she had made in October 1875, left the bulk of her estate to Christchurch's Anglican bishop for religious and charitable works.
[2] After he death, her friends contributed funds for a memorial window in the chapel in the Barbadoes Street Cemetery, and former pupils gathered funds for two memorial windows designed by architect Benjamin Mountfort and placed in the south-eastern corner of the Church of St Michael and All Angels.