A look inside the secret bunkers that held key to D-Day landings

A huge underground bunker was built in 1942 underneath the Victorian-built fort in South wick. It housed the operations centre which coordinated the D-Day landing son the beaches of Norm andy and supporting airborne operations on June 6,1944.

Deep underground, hidden beneath Portsmouth’s Portsdown Hill, can be found the remains of the operations centre which helped bring about what was to be the turning point of the Second Wold War.

The labyrinth of tunnels was the home of 700 men and women of the Royal Navy, Army, RAF and Allied nations who worked on Operation Neptune - the naval phase of the D-Day operation. It also has a direct link to the nearby Southwick Park where Supreme Commander General Eisenhower was based in the weeks leading up to D-Day itself.

The dedicated personal in the operations room processed the key information which gave Eisenhower the latest situational information on the Normandy Beaches and English Channel which was key in the planning of the operations. The wall map at Southwick House – on which the work of the staff at UGHQ was based – can still be viewed by the public today by appointment only.

Many of the tunnel scan still be seen today in special tours including one organised by Hidden History taking place on July 1 and the D-Day Story museum in South sea also features the work of those who worked at Fort Southwick.

The Fort' s connection to the D-Day story has kept it front and centre of our city’s history, however originally it was built to defend the landward approaches to the naval base on the recommendation of the Royal Commission on the Defence of the United Kingdom which reported in 1860.

Construction was started in 1861 and completed by 1870 and it was designed to house a large complement of men in a crescent-shaped bar rack block and armed with 23 guns. It also holds the water storage tanks for the other forts along the hill and, being the highest on the hill, supplies them via a brick lined aqueduct.

Although disarmed in 1906, the fort was retained by the military as a barracks, and also used to train soldiers how to capture and hold a fort and became a demobilisation centre for three years after the First World War. The fort ceased operational use in 2002.

The information which was gathered by the personnel working underground at Fort Southwick was fed to the D-Day plotting room

Duty Wrens pose outside Fort Southwick with their C/O Commander Titheridge.

The main telephone exchange beneath Fort Southwick

A few months after D-Day, The News’ wartime photographer Victor Stewart was allowed into the top secret maze of tunnels beneath Fort Southwick from where D-Day operations were controlled

The News photographer Victor Stewart was allowed into the top secret maze of tunnels beneath Fort Southwic. Here is the Movements office

Wrens of the communications branch during the Second World War

The Plotting Room, deep in the heart of Fort Southwick

Telegraph equipment kept in the maze of tunnels

The exterior of Fort Southwick, May 1980