And to think it was nearly lost when the hands of the city's corrupt council wanted to demolish the hall in 2007. Their eventual sacking the saviour of this extraordinary instrument.

Renowned jazz pianist and composer Mike Nock stumbled upon the the Town Hall beauty during rehearsals for a concert at the Music Lounge earlier in the year, and couldn't wait to get his hands on it.

It is of course the Sharp Organ - one of only 20 built by Ronald Sharp - which played a key role in the craftsman being chosen to build the Grand Organ in the Concert Hall of the Sydney Opera House.

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The organ is not your usual sell-out drawcard, but often features in orchestral concerts (such as from the Australian Chamber Orchestra) or at the annual Lady Mayoresses Afternoon Tea Dance.

But on December 4, Nock and his friends will jazz up the hall - literally - working his magic with the 1537 pipes in casework of polished Tasmanian blackwood.

Think of it like an improvised jam session of jazz.

"The only other time I've played an organ was ... at a friend's wedding, now they're since divorced so I don't know if that had anything to do with me," laughed Nock.

"Curiosity killed the cat, well in this case it may kill me, but whatever."

Nock - who turned 80 in September - is no spring chicken to music having been a "major force on the international jazz scene" for 50 years, according to Eric Dunan, Director of Jazz Studies at the Wollongong Conservatorium of Music.

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Dunan is partly responsible for introducing Nock to the mighty beast earlier this year.

"Some of the musicians wandered over and were like 'whoa, look at that', this massive pipe organ, and they just started doodling around on it," he said.

"Then Mike showed up and we just got to talking and we thought, 'hey man, let's do an improvised show featuring this incredible instrument'."

Nock visited in early November to get better acquainted with the beloved Town Hall organ, something he said was "a steep learning curve, but whatever".

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He said his biggest concern was adapting to not being able to control the volume of the sound, whereas a piano's volume will depend on how hard you press the keys.

But, like a true jazz fiend, Nock oozes a cool, calm and "go with the flow" persona so navigating the dual keyboards, multiple levers and pedals was not a problem.

The Town Hall organ was built by Ronald Sharp between 1966 and 1968 commissioned by Wollongong Council, though remains "unfinished" according to its creator.

"My aim was to make everything as perfect and as long lasting as possible ... they spent £20,000 and I gave it to them half-price," Sharp told the Mercury in 2014.

"They should've spent £50,000 and given me three years, but they wanted it in 18 months. I wanted to spend time here making it a little bit different but it didn't happen."

The organ is one of 20 the craftsman built, on a list which includes St Mary's Cathedral (his first in 1959), Canberra's Church of St John the Baptist, Perth Concert Hall, the chapel at Marist Brothers in Kogarah, and Monash University in Melbourne.

The organ may not be the star of many shows, but its black and white keys are far from neglected.

Fondly known as "the organ lady" to many, Lorraine Jones is one of five organ players who regularly volunteers to give the Sharp pipes a workout, to ensure it remains in top condition.

The octogenarian learnt to play piano at the age of 10, later being taught the organ at Wollongong Town Hall in the 1970s by Robert Ampt (once the official City of Sydney organist).

Mrs Jones was also the first to try out the grand pipe organ after its $91,000 two-year restoration in 2004.

The hall is not usually open to the public on these days, but passers by may here the ethereal pipe sounds drifting through the air.

Meantime, the upcoming improvised jazz night is possibly a first for the grand organ, and something not seen often around the world - possibly because there aren't that many organs of this size.

"It's purpose built for the hall, so you're actually playing the hall," Nock said.

"It is quite impressive when you realise the amount of work that's gone into building these things.

"The whole trip, it's quite an amazing and even a humbling experience."

Mike Nock & Friends: The Pipe Organ Sessions, Wollongong Town Hall, December 4. Tickets and details: www.merrigong.com.au