The curator leads you to a basement entrance and asks you to don a hard hat and follow her into a complex of tunnels containing strange, old-fashioned scientific equipment - metal globes turning on spikes, ballbearings balanced on top of silver plates, wooden boxes with arrays of switches controlling frequency, oscillation, intensity.

These, she explains are Ethometric Instruments. They work through super-electrical harmonic realignment, and can have effects on both physical and psychological states. They have such exotic names as the Etherlux Magnifier, the Sonaesthetic Oscillethergraph and the Ethomagnetron.

Things really get going, though, when Professor Ray Lee enters and begins a demonstration of the instruments, prowling the tunnels to flick switches and twiddle knobs, producing a strange, alien, ever-changing sound world, at once beguiling and disconcerting.

This is hardly theatre, but as a fascinating sound installation with a strange, never-quite-clear back story, it's an astonishing experience. To stand in darkened tunnels surrounded by whizzing, purring, squawking boxes with red LEDs spinning arcs in all corners is an unforgettable experience.

There's a nostalgic charm to the whole thing, and a celebration of eccentricity - somehow it all seems very British. And there's always the possibility, of course, that it might all be real.

- David Kettle