Concealed perhaps 30 metres down, the tunnel runs beneath Memorial Drive from off Nesca Parade below. It spears through pebbly rock to emerge at a former searchlight bunker high up on the cliff (pictured) facing the ocean.

The concrete and brick-lined tunnel runs for about 150 metres under Memorial Drive south of the popular Strzelecki Lookout to allow the vital searchlight to operate in the 1940s.

Never officially open to the public, the now sealed-off tunnel was a vital part of Newcastle's coastal defences at Shepherds Hill, at the top of King Edward Park, in World War II.

This hill site, once controlling big close-range guns, a radar unit and large ocean searchlights, was also possibly unique in Australia.

Personnel from all three of the nation's armed services - the army, navy and air force - once served here together searching for enemy submarines and warships along our coast.

The Shepherds Hill coastal battery was there to help protect Newcastle. The city was a vital cog in the nation's defences, producing munitions and weapons for the war effort as well as being a major ship building/ship repair centre with BHP Steelworks and Williamtown RAAF Base also based here.

The precautions proved their worth when a Japanese submarine surfaced far off Nobbys one morning in June 1942 and proceeded to shell the city at least 21 times until repulsed by extremely accurate return fire from Fort Scratchley's twin naval guns.

And the long, now decaying, tunnel beneath Memorial Drive was also regarded as a key component in defending WWII Newcastle. The tunnel enabled cables to be laid to supply the area's No.1 Searchlight embedded in the cliff face to cover a potential "blind spot" along the Hunter coast after nightfall.

The searchlight crews had the task of covering the flank of Shepherds Hill, the long, southern sweep of Pacific Ocean almost down to Redhead.

Hunter Water Board engineers are credited with driving the long passage right through the hillside below Memorial Drive in 1940. The concrete searchlight engine room, built to withstand even bomb blasts, may not have been finished until 1942.

Today, what is left of the engine room is located on private property with no access permitted. Part of the building is recessed into the hill and the former main entrance doors of steel are now boarded up.

For long after WWII's end in 1945, probably in the 1960s, a block of units was built directly on top of the wartime entry point facing Nesca Park. The former view of the tunnel from the street is now obscured, leaving few clues the 1940s tunnel ever existed.

Once manned 24-hours-a-day with a diesel generator to operate the powerful No. 1 searchlight, it was, however, not alone.

Further north, spalling concrete remnants of the former No. 2 light are now barely visible along with a shrub-covered engine room deep in King Edward Park below the old bowling club land.

Today, the story of the old surviving wartime tunnel beneath Memorial Drive seems like a myth, but it was one of several other city WWII tunnels, most now long since buried.

Many years ago, misguided youngsters scaled the crumbling, ocean-facing cliff trying to gain access to the old, corroding No. 1 searchlight bunker itself. That's perhaps why someone later erected a brick barrier just inside to deter further dangerous and foolhardy attempts.

In recent years, Newcastle City Council confirmed the existence of the 'forgotten' tunnel. In 2013 it featured on the Lost Treasures program by former ABC Radio broadcaster Carol Duncan who highlighted the site being on private property and hazardous.

The tunnel again came into view in 2019 within a lengthy Heritage Council of NSW Conservation Plan of Management on the Shepherds Hill defence group of military installations.

The report's authors concluded this particular group of Newcastle wartime coastal defences were "historically significant at a state and possibly national level".

As a callow teenager, possibly in the late 1950s, I remember being intrigued and exploring an empty corroding WWII concrete bunker up a hill. The big metal doors were ajar. No lock. The location must have been open for years back then and a bit of a magnet for other curious kids.

Someone back then was using what would have been the historic old No. 1 searchlight room as a temporary laundry.

A little further inside the dark and dank T-shaped, man-made 'cave' was a long, very draughty tunnel. There was water underfoot and a colony of disturbed bats, squeaked somewhere in a dark recess.

There was the tang of salt air in the gloom and at the far end there was a small, welcoming square of daylight. It was smelly, dirty and dark, cold, a trifle claustrophobic but no graffiti marked the walls back then; that took another generation, of two, armed with aerosol cans. We were only intruders back then, not vandals.

Today the corroding tunnel is well hidden and probably best forgotten, a relic from the past with hidden dangers.

Nearby Strzelecki Lookout became well known to the public for its water tower only after Memorial Drive itself was created down to Bar Beach, opening in October 1922.

The general site has become popular again, with the erection of the landmark Anzac skyline walk, the extraordinary WWI memorial bridge which opened on April 24, 2015.

As for the wartime tunnel deep beneath, well, I've never mentioned it before but I was reminded of its existence recently when yarning to long-time Newcastle resident Mrs Amelia Ross, now 88, about life in the 1930s Great Depression and beyond.

"There was once only one house standing on Memorial Drive, possibly in the late 1940s, or after," she said.

"It was an A-frame house. It's still there today. There was so much grass on the empty hillside looking down towards Darby Street that we used to call it 'The Prairie'.

"The Memorial Drive tunnel entry was also down there. It was pitch black inside and stunk, like a swamp.

"We used to slide down that hillside, towards today's Nesca Park. At that time 'Nesca Dam' was still at the bottom. It was a large old Cooks Hill colliery dam, but it's all gone now, it's been drained and become parkland. Amazing how landscapes change over decades."