Given the arty context - and context happens to be central to this piece - we were braced for anything. Animal carcases in formaldehyde? Rotting offal? None in sight. Instead, we were led down the corridor towards the mirror, stepping with difficulty over concrete beams (which, the guide pointed out, mirrored the concrete beams in the ceiling), then let out at the other end.
Was that it? Yes, except that Mirror Mirror, as it is called, breaks boundaries that Damien Hirst has not yet broken. It is not just that it is probably the biggest art "installation" in Europe. It is a "site-specific" installation - one that attempts to relate to its environmental context. It also envelops its viewers, inviting their participation in the whole. Site-specific artists aim to go beyond merely exhibiting art objects in a "White Cube" - which is the art trade's tongue-in-cheek term for a gallery and, ironically, the name of the London gallery that shows Damien Hirst.
The discomfiture of some members of the coach party after experiencing the concrete obstacle course arose from the suspicion that perhaps we had just visited Pseud's Corner. Oh, dear, did we really need more difficult art? To find out, a couple of days later, I took a lunchtime offering of sandwiches, custard creams and peaches to the car park - site-specific to Stanway Street, where the Space Studios trust has converted much of it into artists' studios - perched on rickety chairs with the creator of Mirror Mirror, Jacqueline Pennell, and asked her: "What's it all about?"
Pennell, aged 34, graduated from Goldsmith's College before it became famous for fixing up superbrat artists like Damien Hirst with trendy galleries even before graduation. Dust from the 15 bags of cement that went into the installation clung to her black builders' boots. She spoke quickly and precisely.
"It's about reflecting on yourself. The piece is not complete without the viewer bringing something to it. Until now, my pieces have been smaller and there's been the possibility of interfering with them physically. Surrounding the viewer with the artwork is a major step. The viewer becomes centre stage. I set up the piece to look at you.
"You could walk into the space and say there's nothing there. But if you start looking, there's an awful lot - not only the building work that's been done but the image of yourself within the artwork. You have the experience of approaching yourself in the mirror and then when you turn round again you are facing a blank canvas. I wanted that sort of progression - a journey through an artwork that also represents the making of the artwork. The whole experience you have is of being within the piece."
Even for people with no art training? Where's the benefit for Joe Public?
"I think they can respond to it. To some extent it's familiar territory - architectural features like waste pipes, window grilles, concrete beams and a canvas, which everyone knows is to do with painting. But, at the same time, I think a lot of people will experience that it's not quite right. There are extra waste pipes, for example, that mirror the existing ones and whose bend is not the right way up. Whether you are visually educated or not, you will start to notice these things.
"Then you start to see yourself in the mirror. Perhaps the connection between yourself and your mirror image, seen against the canvas behind you, might take some time to become apparent, but most people are familiar with playing around with their own image on video, that sort of thing. I'm not presenting people with a painting on a wall and saying, 'this is the artwork, look at it'. I'm saying, 'walk in, people such as you are part of it'. I'm asking them to participate. I'd have thought that people not used to art would have found that even more enjoyable. It's very physical.
"You don't have to do mental gymnastics or ask the meaning of this or that - just relate to what's going on."
So what's the point?
"I'd hope that any piece of mine would make you more aware of how you operate physically within the world, help you to look more carefully at the things that stimulate you visually, to realise how important they are, how they affect your whole being. You look at yourself in the mirror, learn something about yourself, perhaps, become more self-reflective in a positive sense."
Pennell's work has never been taken up by a gallery - though her cv is crammed with exhibitions, awards and grants, commissions and artists' residencies. She is one of London's hundreds of young, scratch-a-living, professional artists whose names are familiar to art circuit impresarios such as the Saatchis, Karsten Schubert and Jay Jopling (Damien Hirst's gallerist) but do not yet trip off the tongue of the man in the street. Or even the man in the indoor car park.
Mirror Mirror, her first major solo exhibition, could mean a lot to her. But even its concept is virtually unsaleable. The project has outstripped its pounds 1,000 budget and she will count herself lucky to get her pounds 500 fee from Rear Window, the art organisation specialising in site-specific art which commissioned it. She earns her living from part-time teaching at Chelsea and Camberwell art colleges, on one-term contracts. Her last sale was five years ago - a wall sculpture for Railfreight's London headquarters that earned her pounds 1,000 from a corporate art agency. By autumn, she expects to be pounds 700 to pounds 800 overdrawn at the bank, having spent the summer invigilating Mirror Mirror, scouring newspapers for teaching posts and residencies, and drawing the dole.
Why do it? "It's a quest, a way of working that continually generates questions and answers. Nothing fascinates me as much as this."
The roving Rear Window, administered by Jean-Paul Martinon and Peter Cross, specialises in site-specific projects. Its best known is last year's Care and Control, set in Hackney Hospital, a 270-year-old former workhouse turned psychiatric hospital. More than 30 mentally-ill patients and 18 artists were invited to create artworks recording the experience of mental illness and its environment. Names were published but not diagnoses. One patient, Jill Cleghorn, turned the service lift in A Block into a padded cell.
Martinon traces the antecedents of site-specific art to the building of the cathedrals. Their paintings, statuary, frescoes, were designed as a whole. It was during the 18th-century Enlightenment, says Martinon, when princes took over from popes as the chief art patrons, that art objects became detached from their contexts. He wants to put them back together.
Whisper it not, but site-specific art has a more recent, less-elevated provenance - in the Edwardian tea rooms of Glasgow. It was the Scottish architect-designer Charles Rennie Mackintosh whose integrated interiors - with murals, furniture, lighting, cutlery, even waitresses' uniforms, all in harmony - for the redoubtable restaurateur, Kate Cranston, re-established the principle of total artwork. The avant-garde artists of the Austrian Secession hailed it as Gesamtkunstwerk and feted Mackintosh as a master.
Seekers of contemporary site-specific art could come across a terrace of houses with a yawning gap and faded photographs of Jews on the exposed gable ends (Christian Boltanski's Missing House in Berlin), a waist-high floor of black motor oil mirroring the ceiling (Richard Wilson's 20/50, remade for the Scottish National Gallery and bought by the Saatchis) and a roomful of exploded furniture that disperses the attention (Arakawa and Madeline Gins). Pennell's earlier site-specific installations have included last year's Deadlock at the Chelsea Physic Garden - a trompe- l'oeil garden cloche of mirror glass, filled with gravel and sited on a gravel path.
Among site-specific's modernist echoes - Constructivism, Dadaism, Surrealism, Pop and conceptual art - the American land art of the Seventies bulks massively. Michael Heizer excavated 240,000 tons of earth in Nevada to create Double Negative, "a peaceful religious space". Christo wraps mountains, islands and buildings in millions of feet of fabric. The Brits Richard Long and Andy Goldsworthy complement landscapes with monumental rock formations.
Less monumental, Mirror Mirror was nevertheless a "heavy piece" for Pennell. It consumed, besides the cement, 50 bags of sand, 15 boards of 8x4ft Sterling compo and 10 boards of 8x4ft shuttering ply. It took 20 volunteers - her students and artist friends - six weeks to construct, during which she ferried building materials in her Austin Maestro B-reg van and had a love affair with an extra-macho Hilti hammer-action power drill with 18in bit. "Where d'you want the hole, luv?" became her catchphrase.
We did find a lone punter to respond to Mirror Mirror as we ate lunch beside it. Warwick MacCallum, a 56-year-old picture restorer from Islington, walked the concrete corridor and declared: "I found it terribly tranquil and satisfying. You look at the mirror and feel soothed." Pennell looked rather stunned. Supposing he had found it pretentious, or rubbish?
"Then I'd start by asking whether it had made him think about anything at all. Was his mind completely blank? Artists can't answer all the world's major questions but we do set out to touch something in the viewer."
Does the interpretation of conceptual art need to be learned?
"The viewer has to understand that looking at art can be hard work. But it's the artist's job to enable the average person to see. When you're making a piece, you're constantly asking yourself: 'What's going to be the first thing that takes the viewer's attention? Is that what I want to happen?' At the same time, viewers are not stuffed vegetables. Looking at art is a two-way thing, like a conversation. The artist should not be expected to do all the talking. The viewer engages in the conversation, becomes animated by it."
Later, I spotted a peach stone lying in an empty tinfoil case from a custard cream and asked Pennell to interpret it. "There's someone's presence here, someone has just passed through, so we're thinking about their identity," she began.
Not just rubbish?
"Even rubbish has some thought behind it. But it is just rubbish, innit?"
"Innit," I said.
! Mirror Mirror is open until 15 September, Tuesday-Sunday 12noon-5pm, at the Sara Lane Studios, 60 Stanway Street, London N1. For further details call 0171 739 3707.Reuse content