St Peter's Anglican Church
Old South Head Road, Watsons Bay
1796 Gray (London) 1/7 mechanical
From the 1988 OHTA Conference Booklet:
It is doubtful whether there is a more picturesquely sited church in Sydney than that of St Peter's Watsons Bay. Situated on the western side of high cliffs which form South Head, the church has magnificent views of most of Sydney Harbour.
The organ in the west gallery is probably the oldest pipe organ in Sydney. The instrument was documented by John Stiller, OHTA Research Officer, in October 1980, and the following observations were made about the history of the organ:
1796: Organ built by Robert and William Gray of London, for the Hon Spencer Perceval who later became Chancellor of the Exchequer. Legend has it that the organ was lent to the Emperor Napoleon, and after his fall in 1815 was brought to England in 1817 by Lady Perceval, who ordered it to be sold. This has not been able to be confirmed.
1829: The organ was in the possession of the Congregational Church, Wiveliscombe, Somerset U.K. It remained there until 1915, It was bought by Dr.C.A. Edwards of Sydney (who was born at Wiveliscombe) in 1901. But the then organist was so distressed at the passing of an instrument upon which he had played so long, that the Doctor agreed to forego his purchase. During World War I Dr Edwards had another oportunity of visiting his native town. He was then able to renew his offer for the purchase of the organ, which was accepted
1915: The organ was installed in the Small Hall of the N.S.W. State Conservatorium of Music, Sydney.
The organ in the NSW State Conservatorium of Music c.1916
1920: Organ installed at Watsons Bay.
1965: Some renovation work undertaken by Roger Pogson, including the installation of Mixture pipework.
Alterations which have been made to the organ include:
1. Addition of a pedalboard and Bourdon pipes.
2. Original short octave GG compass reduced to standard C-f3 compass;
3. Removal of the original Cornet/Sesquialtera register, its replacement by a Gamba 8' and its subsequent replacement by the Mixture III. 
It is interesting to note that most of the remaining pipework is original, although tuning slides have been added and the pitch altered through the transposition of pipes. The organ's interest is further enhanced by an attractive mahogany case, a console which retains many original features and the retention of the original key and stop actions.
From Historic Organs of New South Wales (Rushworth)
The specification is:
Stop Diapn Bass
Stop Diapn Treble
Manual to Pedal Coupler
Mechanical Action throughout 
from the 1988 OHTA Conference Booklet
Colour photos taken by Pastor de Lasala 2007 (copyright)