When Newhaven Fort was handed over to civilian control, it was in immaculate condition. Sadly, this was to change. Having paid £13,000 for the structure, the local council simply did not know what to do with the site. To be fair, there was not the interest in national heritage that there is today and certainly not the money available to preserve it.

Many grandiose schemes were put forward for using Newhaven Fort as a public space and the site was eventually leased to a private developer. In spite of local protest, the developer turned Newhaven Fort into a holiday camp and proceeded to demolish structures on the ramparts, bulldozing them onto the parade ground below. The moat was filled in with silt from the new marina, (then under construction) and rubble was crammed into the tunnels. The fronts of the casemates were ripped out and most of the buildings on the parade ground flattened. Outside of the fort, the old drill hall and other buildings were also demolished and the houses on the old eastern gun battery, overlooking the harbour, were built.

The project failed and the Fort was left in a state of disrepair. The destruction was made worse by vandals and thieves who wrecked or stole much of what remained of value or interest.

Even though Newhaven Fort defied total destruction, by the end of the 1970s it was in such a poor state that it became little more than a dangerous, unofficial playground for local children. Most of those interested in its preservation had given up all hope. However, unlikely as it seemed, all was not lost.

Just as things seemed beyond redemption, Newhaven Fort was declared a scheduled ancient monument in 1979. Next, two local developers approached Lewes District Council (which had now taken over control from the local council) with a proposal to transform Newhaven Fort into a leisure centre. This was approved in 1981 and work started shortly afterwards. Great care was taken to restore as many features as possible, starting with the removal of some 800 lorry loads of rubble and partial excavation of the moat. The casemates were reinstated, even using re-claimed Victorian glass in the windows.

On the 7th April 1982, under the title “Fort Newhaven”, the general public was invited to a grand opening ceremony. General Sir Harry Tuzo GCB, OBE, MC, Master Gunner of St. James’s Park unveiled a plaque to declare the fort officially open.

A chequered period followed, and by 1985, running the fort as a private venture had failed and the site was closed.

Lewes District Council decided to run the fort itself and in 1988 reopened it as a military heritage attraction. A large collection of artefacts had been accumulated and formed the basis of early displays. One important decision was to reinstate the fort to its correct title, Newhaven Fort.

In spite of the excellent work carried out by the original restorers, a great deal was still needed. Thanks to a £1million lottery grant, a huge programme of restoration was able to take place in the late 1990’s. Much of the work was basic, but essential, including pointing all of the brick work.
One of the most important task was “tanking” (waterproofing) the roofs of the casemates, allowing the Officers Quarters and "The Fort Showcase" to be used for the first time. The entrance bridge was rebuilt and the chimneys faithfully replicated to original specification. The restoration programme was completed for the new millennium in 2000, but further works are still needed.