On 22 May 1913, following the resignation of Andrew Harper, Ferguson was appointed Senior Chaplain and Chairman of the exclusive Presbyterian Ladies' College, Sydney Council, retiring in 1923 due to ill health. Whilst in this role, he actively worked towards the planning and establishment of the Presbyterian Ladies' College, Pymble in 1916, a branch of the Presbyterian Ladies' College, Sydney. He was also the first chairman of the board of the Australian Inland Mission, a member of the Council of The Scots College and St Andrew's Theological College, and Vice-President of the Highland Society of New South Wales. He was also to become the Acting Principal of St Andrew's Theological College at the University of Sydney in 1917.