Uncovering the labyrinth below Portsmouth Dockyard in 1997

Robbie Woodcock, a maintenance engineer, examines one of the tunnels that run more than two miles underground.
Robbie Woodcock, a maintenance engineer, examines one of the tunnels that run more than two miles underground.

Deep beneath Portsmouth’s naval base lies a labyrinth – about two-and-a-half miles of tunnels and chambers, some of which dated back 400 years. 

At the heart of this intricate maze is a cavernous, underground reservoir. It was dark, echoing, knee-high in foul-smelling water and inhabited by rats.

But little was known about the dark tomb and few people were aware of its existence. 

However, it was Robbie Woodcock’s responsibility to maintain the base’s dry docks and locks. And as part of the job he began more than 30 years previously, the 55-year-old regularly walked through the tunnels underneath the base.

Mr Woodcock soon became interested in the reservoir – an underground chamber 33ft deep, 145ft wide and 254ft long, that was around 50ft beneath the old Block Mills and just a few hundred yards from HMS Victory.

And he had discovered that in the 1700s, it proved to be the engineering breakthrough which enabled dry docks at Portsmouth to be pumped clear of water for vital repairs to ships faster than any others in the world. 

Mr Woodcock said: ‘There have always been rumours about what this was used for but the stories often turn out to be half myth and half fact, so we will never really know.’