Sometimes when you follow a lead, you get more than you bargained for. This was very much the case one evening when we set out to see what the truth was in there being over a kilometer of tunnel under an area of the city. Turns out, it was true. And there was more than we had expected at the end.

We suited and booted in our finest hi-vis disguise and I popped a hard hat that I'd found on a rooftop on my head. A mass kidnapping of cones and signs from around the city then commenced. The door flung open, and the poor unsuspecting cone was hauled into the vehicle with no opportunity for protest.

The cones were deployed in a fashion that was deemed to be authentic enough, the manhole was lifted, and down we went.

These century old tunnels were built to carry electricity cables for the trams that once existed. Now, they're still used for electricity, but have been taken over for high voltage distribution.

Expecting the tunnel to terminate in a wall with cables disappearing into it, we instead found that the tunnel emerged in the basement of what was the power station - an almost church-like building now just seemingly a storage place for substation components. Underground, signs remained reminding of previous use and up top, the blacked-out building lay silent.

We'd only gone down a few hundred metres of tunnel, so what about the rest? A quick look the previous night had told us that the next section of tunnel was partially flooded. So, returning with wellies, the DIY "road works" kit was deployed once more and the hole popped.

The remainder of the tunnel was long and terminated at nothing in particular, but was interesting nonetheless.