Many organs made by F. W. Walker of London were imported to Australia during the 19th century. J. W. Walker & Sons Ltd is a British firm of organ builders established in 1828.

The importance of organ music and the need for an organ at St Thomas’ Church was explained in a Sydney Herald news article published in August 1840: ‘… The choir a most delective and often discordant body… A trifling subscription from every Church-goer would provide an organ, and we are sure that many vocalists would then be found to join in the performance of the most grateful and sublime part of public worship…’.

Funds to purchase the organ were raised by St Thomas’ parishioners and one of the Church’s early instruments, a Seraphine, was sold. When the organ arrived in Australia, there were further expenses to fund packing cases and freight from Sydney to Port Macquarie. The incumbent minister Rev. John Cross gave a liberal donation of £32 towards the outstanding debt. The organ remains as a legacy to his thirty-year service as St Thomas’ Chaplain.