Called Rathmines, this idyllic southern lake suburb remains a very tranquil spot. A place of quiet reflection. Only birdsong and the sound of an occasional passing motorboat, or car, normally breaks the silence.

But between 1939 and 1961, especially during World War II, it was a totally different story. Back then, the scene was alive to the sound of revving motors, seaplanes taking off, marching feet and the hum of machinery.

That was when the then out-of-the-way Rathmines, set in dense bush, was the largest flying boat base in the Southern Hemisphere. It was protected by a hidden gun emplacement at Wangi and a secret radar shield at a hilltop timber tower (since demolished) with concrete igloos at Catherine Hill Bay.

But a decade or so after WWII ended, the waterfront suburb began to slip back into obscurity, and its crucial role in protecting Australia was almost forgotten.

Many of the buildings, including seaplane hangars were sold, leaving big swathes of land unoccupied, including a large concrete launch pad into the lake. The property is now owned by various entities, including Lake Macquarie City Council. The remains of the former strategic RAAF base were only added to the NSW State Heritage Register in late 2005.

It seems hard to believe now, but during its relatively brief but busy 22-year existence as a major air base, Rathmines was home to at least 10 separate flying units at various times, including the RAAF's No.11 and No.20 squadrons. The Rathmines site, also remains the most intact example of an RAAF WWII seaplane base in Australia.

But it also has a more fascinating past, a secret officially held for 60 years. The vast extent of the invaluable, often uncredited work carried out by RAAF Catalina aircraft and their crews in the South West Pacific only gradually became more general knowledge from the 1980s onwards as the few surviving wartime airmen grew old and tongues loosened.

But as the work of the slow, long-range Catalinas (also known as Black Cats) was a true coalition between the RAAF and US Navy in WWII, almost all of the official documents involved were sealed in Washington archives - and often unopened - until 2003.

Former RAAF Black Cat crews were sworn to secrecy at war's end in 1945 in case a successful technique of mine-laying distant enemy harbours in Asia might be required again in the near future. (Maybe the allies already had fears about the looming conflict on the Korean peninsula in the early 1950s.)

That top secret history of the widespread Catalina mine-laying operations to cripple Japan's war machine is told in an engrossing new book, RAAF Black Cats, by Robert Cleworth and John Suter Linton. But more about that in a moment.

For now, let's look at a permanent reminder to the courageous air crews at Rathmines flying boat base during those dark days of WWII when Australians feared invasion was imminent.

But it's not the memorial tower propeller on the point there, but rather the building nearby. It's called Club Catalina, or more properly, the Catalina Memorial Bowling Club, better known as 'the home of the Catalina'.

This neat, single-storey bowling club, still largely intact, was once the Rathmines RAAF officers' mess. Erected in 1940, it served until 1961 as the off-duty hub of activities. About 200 officers regularly used the facility.

When the RAAF base ceased operations, lake council bought the site, and in 1971 it was leased to become the Rathmines Country Club. In 1974, the club expanded with a bowling green and the site was renamed.

In honour of the men and women who served at Rathmines in WWII a memorial wall was constructed inside (see picture) in 1984. It features a leadlight window depicting a Catalina amphibious aircraft with memorabilia. The club was also then given its present name.

Another reminder of the club's past are seven impressive model aircraft (of the type once seen at Rathmines) suspended from the ceiling near the club bar.

Now, some more background. Although many different aircraft used the former lake air base, it was the giant Catalinas, the twin-engine, long-winged flying boats (with a wing span of 104ft or 31.69m) which were mainly identified with Rathmines RAAF.

Despite being slow and vulnerable, the 'Cats' (or PBYs - for patrol bomber) were very versatile, normally used for escort duty, anti-submarine sorties, long-range reconnaissance, plus supplying and rescuing the Aussie coast watchers behind enemy lines. They were also the first in and last out after WWII ended, evacuating our prisoners-of-war.

The Catalinas were named after an island off San Diego, California, close to where the PBYs were originally built.

Carrying a crew of up to nine, some of the wartime era aircraft had been still flying around the world until recently as water bombers. Tragically, more than 300 Catalina aircrew died in service in WWII.

The new book, RAAF Black Cats, does them proud, finally lifting the veil of secrecy on the operations made in the Pacific War to ensure final victory. It started when co-author Robert Cleworth started investigating what really happened to his late airman brother, Reg, who trained at Rathmines, and then went missing on a mission out of Darwin in March 1945.

Reg was involved in the more dangerous tasks of the Pacific War - long range bombing and mining distant Japanese occupied ports, flying often in total darkness at the suicidal height of 100 ft (30.48m) near their targets.

To lighten the Catalina weight for mine-laying, protective aircraft armour was removed and it was not uncommon for their .50 calibre machine guns to jam.

The aerial mines dropped bottled up enemy ships in harbour, or forced incoming ships to avoid shallow port channels and divert out into sea lanes where they were a prime target of waiting Allied submarines.

One historian even claimed that the aerial mine-laying campaign was 40 times more effective than bombing of land targets. Three RAAF squadrons made 230 sorties against 18 enemy harbours, closing 10 harbours for up to five weeks and sinking about 54,000 tonnes of shipping.