Britain's biggest purpose-built air raid shelter, which could hold 6,500 people, was so sophisticated it even had electric lighting and flush toilets. The tunnels were dug into sandstone cliffs along the River Mersey in Stockport in the 1930s, and were originally intended to provide car parking spaces. But following the outbreak of the Second World War, the space was redeveloped as an air raid shelter where residents of Lancashire and Cheshire could hide from Nazi bombs. Scroll down for video . Shelter: This shows one of the rooms of Britain's largest purpose-built air raid shelter, located in Stockport, Greater Manchester . Safe: A bunker lined with corrugated steel to protect against the possible effects of a Nazi bombing raid during the Second World War . Tunnels: A total of 6,500 people could fit into the shelter, which was made up of a network of interconnecting passages . Entrance: The shelter has been converted into a museum, replicating the conditions which would have been found 75 years ago . The shelter became so popular that local officials had to issue season tickets limiting the number of people who would be allowed to seek refuge there. The cliffs were first dug out to provide cellars for homes along Chestergate, one of the busiest streets in Stockport. As part of a plan to widen the roads, the local council bought and demolished the houses, and planned to convert the cellars into an underground car park. An engineering survey showed that the space was in fact unable to become a car park - but the advent of war meant that it was needed as an air raid shelter. Bathroom: The women's toilets, equipped with a proper flush, located deep inside the Stockport air raid shelter . Gadgets: A radio, blood pressure monitor and lamp from the 1940s, pictured inside the air raid shelter's first aid section . Medicine: The shelter had a first aid room to help any residents who were injured by the bombing raids . Equipment: Gas masks which were kept in the shelter are pictured left; right is the sick bay, where people could seek shelter while unwell . Extent: The shelter was going to be turned into a car park, but officials discovered that its long tunnels were unsuitable for the purpose . Curator Howard Green said: 'The official capacity was 3,850, so outside they painted 4,000 - but what they didn't advertise was that they thought they could squeeze twice as many in if needs be. 'They were used extensively by people from Manchester and Salford, and even as far as Eccles. Stockport was less of a target, and the underground shelters were a particularly safe place. 'What they did was introduce season tickets - they were issued to locals, although you could write in if you had difficult circumstances. We still have some letters from people in Manchester who'd been bombed out several times. 'It was really only a way of damping down demand, nobody was denied entrance in an alert. In the winter of 1940 and '41, it went up to 6,500, with another four sets of tunnel shelters. History: A photograph of the shelter as it appeared in the 1930s, around the time of the Second World War's outbreak . Rambling: The tunnels were large enough to fit in 6,500 people, who came from all around Lancashire, Cheshire and Manchester . Emergency: Local councils had to establish air raid shelters to protect their populations from German bomb attacks . Base: The room belonging to the shelter's warden, who would have been responsible for ensuring the safety of those inside . Danger: A fire bucket and hose which could have been used to control any unexpected blazes in the tunnels . 'People are always surprised by the extent of them, and just how much thought and planning went into them. There were first aid posts, electric lighting and flush toilets, which people living in back-to-back cottages of town centres wouldn't have had at home.' The shelter space is now operated as a museum, and has been restored to how it might have looked to residents hiding there during the war. Stockport was heavily bombed between 1940 and 1941, but escaped serious damage - unlike nearby Manchester, which as an industrial hub came under sustained attack from the German air force.
Air raid shelter in Stockport was dug out of caves along the River Mersey and intended to be a car park .
With the advent of the Second World War, the space became a shelter which could hide thousands of people .
The air raid shelter was so popular the authorities had to issue season tickets in order to control numbers .