WORKMEN who accidentally uncovered one of the country’s largest World War II bunkers have had to reseal the entrance to make way for a road to be built over it.

Danny Ambrose, of Mellwood Construction, told how they uncovered the impressive 80ft shaft in Leighton Road, Tranmere, which leads to a network of tunnels that stretch 40-70ft deep beneath Olive Mount and Holborn Hill.

He said: “We knew there was a network of caves down there and found a concrete slab, which we presumed was the entrance and we carefully picked away at it for a day or two, we then found the ladders which went into the shaft.”

The entrance has since been blocked to make way for a site of 12 new houses and four bungalows.

It was at the Birkenhead Town Council in 1940 that the go-ahead was given to build two large civilian air raid shelters in Tranmere and Bidston for the protection of Cammell Laird employees and their families.

The tunnel took over two years to build and stretched 6,500ft underground with a final provision to house over 6,000 people.

But not just anyone could have access to the shelter and a ticket system was operated with permanent tickets to be given to approved applicants only.

At one point in 1942, the application for tunnel tickets was 4,259 with 2,305 allocated and 1,626 applications refused.

A library was also built into the shelter and extra heating provided to keep the books in good condition.

All three entrances to the bunker were secured by double gas proof doors to provide security against a gas attack.

By the time the tunnels were completed at a final cost of £131,000 the need for them had disappeared and danger of invasion over.

They were then abandoned and became a secret place for children to explore.

The entrances were finally sealed in 1989 because of the danger of young people getting lost within the maze and falling down the air vents.

Danny Ambrose said the men were told not to go down into the tunnels for health and safety reasons.

But curiosity got the better of one man who told us: “They are amazing.

“I had to take the opportunity as I’d never get to do it again and I spent about an hour and a half down there.

“They are really well preserved, with signs on the walls saying Library, Marshall’s Post, Canteen.”

“One of the rooms had fold down beds, with springs, there were old chairs scattered about and I found an old rusty safe which had been left open.

“They certainly would make a great tourist attraction.”