I attended the concert last night, it was marvellous. Not surprising that a school should have such an instrument, however, and as Sydney private schools go, it's a modest one. My alma mater (the King's School) has a wonderful Pogson organ which is much larger, but then again it's hall is more than twice the size of Grammar's.
The performance
Just about as good as it gets, delightful registrations (considering the limited stop list) and beatifully executed. There was the Grammar School's boy's choir who sang the chorales for the three Passion Chorales (BWV681, 621 and 622 see my sticky thread at the top of this illustrious forum for my typesetting of these works) then the organ played Bach's music. Not distracting at all and a nice touch. The boys were all in year 6 and 7, so around 12 to 13 years old.
The organ
It was actually donated to the school by a chap, who was obviously an ex-Sydney Grammar student. What a gift!! My only criticisim is this: what a shame they didn't use and Australian Organ builder. Now, before you all collectively grind your teeth and roll your eyes, Mander is a fine company, and this is the first organ they've built in the southern hemisphere.
The voicing of the instrument is splendid and for such a small beast it boasted two 16' reed stops (one on the Pedal and the other on the Swell). Loved it, I chatted with the organist at the end and thanked him for his marvellous playing. He's a lecturer at the University of Queensland (Brisbane), I can't wait to see the students he fosters, if they're anything like their master, they'll be fine players.
The stop list
Great
Open Diapason 8'
Stopped Diapason 8'
Principal 4'
Fifteenth 2'
Mixture IV
Trumpet 8'
Swell
Gedackt 8'
Viola da gamba 8'
Voix Celeste 8' (tenor C)
Principal 4'
Chimney Flute 4'
Fifteenth 2'
Sesquialtera II
Bassoon 16'
Hautbois 8'
Pedal
Bourdon 16'
Trombone 16'
(the rest borrowed from the great)
Principal 8'
Bass Flute 8'
Fifteenth 4'
Trumpet 8'
Couplers
Great to Pedal
Swell to Pedal
Swell to Great
Accessories
Tremulant to Swell
64 level solid state combination action
Sequencer
Pitch: A=440Hz
Temperament: Valotti
Manuals: C to a (58 notes)
Pedals: C to f (30 notes)
Mechanical key action
Electric stop action
Number of pipes? 1092