Inside the WW2 plotting room at Sydney's North Head
Seventy-five years after they were closed, the doors to the plotting room co-ordinating the guns defending Sydney Harbour will be reopened.
"It is very nostalgic," said an emotional Glyn Evans, 71, on entering the underground bunker on North Head at Manly where his mother served in the Australian Army in World War Two.
The previously sealed site has been restored by volunteers from the Sydney Harbour Trust and is just one of many parts of Sydney that still carry echoes from the war that ended 75 years ago on August 15 1945.
"I grew up hearing the stories of the time my mother spent here and seeing it today brings those recollections to life," he said.
His mother, Patricia Talberg, was one of the Australian Women's Army Service (AWAS) members stationed at North Head and working round the clock shifts to track shipping approaching Sydney Harbour.
The two giant 9.2 inch guns on North Head were part of Sydney Harbour's defences that also included guns on South and Middle Heads. Observers on the headlands would report shipping movements to the plotting room where AWAS members would physically lie on the chart table to calculate the range for firing.
"They were all picked for their ability at mental arithmetic," Mr Evans said. Accuracy was vital, a single 175kg shell would take 60 seconds to travel 28km out to sea. "You had to know wind speed, climate and how fast the target was moving."
The plotting room and gun emplacements are reached by a series of narrow tunnels carved into the sandstone, 11 metres below the surface.
Volunteer Sydney Harbour Trust guide Ross Downie said: "They hit some kind of stream and 167,000 litres of water runs down channels in the tunnels and into the harbour every day. No one knows where it comes from."
Two workers died during the construction of the tunnels that were completed in 1936. "When I come down alone to turn on the lights I get halfway along and I always feel there is somebody watching me," he said. "It's very creepy."
Mr Downie, who was named after his uncle who was taken by a shark after the sinking of the hospital ship Centaur off the coast of Queensland in 1943, is an expert on the North Battery. He will soon be guiding members of the public around the historic site once the final touches are put to the restoration.
"The guns were only fired in anger once," he said. "To put a warning shell over the bows of a Polish freighter that mistook Sydney Harbour for Newcastle."
However the Harbour did famously come under attack from three Japanese midget submarines - one of which managed to shadow the Manly ferry through a protective net and fire two torpedoes. It failed to hit the USS Chicago and instead sank a converted ferry, killing 21 sailors.
The midget subs were all lost but the Japanese mother-submarines then launched a series of attacks on shipping and fired a bombardment on Sydney that saw shells hitting Rose Bay.
"They did not kill anyone but it had a big effect on morale," Mr Downie said. "It is the only time in history property prices in the Eastern suburbs fell."
Originally published as Inside the WW2 plotting room at Sydney's North Head