Tales from behind the sofa

TOM CHRISTISON is showing off his drawings. The four-year-old hands over a piece of paper on which he has made the usual colourful felt-tipped spirals and shapes you'd expect from a pre-schooler. But it's what he says next that surprises. "This is the Dalek holocaust," he smiles. "That's Tom Baker's last episode."

The reason this boy knows so much about Doctor Who is that his dad, Alan, is an obsessive fan of the series. Doctor Who, of course, has no shortage of admirers; more than 13 million people tuned in on Christmas Day for the most recent episode, and the forum on the international fansite Outpost Gallifrey (www.gallifreyone.com) has 39,000 members. There are some, however, who have gone beyond mere enjoyment of the show and entered the realms of obsession.

Scotland has three long-standing Doctor Who fan clubs – Glasgow Who, Strange Matter in Edinburgh and the Tardis in Tayside Society. This last group, which meets in Forfar and elsewhere in the area, chose its name with an eye to the amusing acronym, though it could be argued that its members missed a trick in not opting for The Runaway Bridie.

Alan Christison is a member of the Tayside group. A 35-year-old with longish hair and glasses, he manages the Dundee FC shop. "Football fans and Doctor Who fans are the same, except our scarves are longer and more colourful," he says with a practised air.

He lives in Arbroath. You know as soon as you walk into his house, even before you're handed tea in a Judoon mug, that a Doctor Who fan stays here. The first thing you see in the hall is a painting of all the Doctors up to and including Paul McGann. There are also three Dalek plaques on one wall – a sci-fi version of those kitsch flying ducks.

After handing each of his sons – Tom and Jake, 11 – signed photos of David Tennant which arrived in the morning post, and keeping the largest autographed picture for himself, he leads the way upstairs and into the loft.

It would be good to be able to report that this space seems bigger inside than it appears on the outside, but in fact there's hardly room to move as it is absolutely packed with Doctor Who merchandise, including a chess set, a large replica of K9 which Christison commissioned, and a shelf of four life-sized Doctor heads (plus his nemesis, the Master) staring vacantly like stuffed moose. There are Doctor Who figures everywhere, still in their packets, and even tacked to the eaves. Christison points to one from the 1980s: "This range is laughed at now. They brought out a Davros with two hands, but everyone knows Davros just has one hand."

In the middle of the room there's an old-fashioned coat-stand from which hangs three outfits that Christison wears to fan conventions. There's Peter Davidson's cream coat and cricket jumper, Sylvester McCoy's Panama hat, and an unbelievably garish overcoat that is Christison's pride and joy. "Probably my most favourite thing ever," he explains, "is this replica Colin Baker costume which my aunt made for me in 1993. Colin himself has seen it and remarked on how good a likeness it is."

Christison, like many of the show's obsessives, sometimes refers to the actors who played the Doctor by their first names, as if they were friends. This is not as odd as it seems; the fans often meet these actors at conventions, which can be quite intimate occasions, and it is possible to share a cup of tea with someone you once watched fighting Daleks on telly.

Alan McWhan of Glasgow Who has been organising a local convention, known as Army of Guests, for the past three years. This year's event will take place at St Andrew's in the Square, an iconic church in the city's Calton district, on May 24. Colin Baker will be in attendance, as will a number of other actors and writers associated with the series.

The members of Glasgow Who meet upstairs in the Crystal Palace, a pub on Jamaica Street, on the first Sunday of each month. I go along to meet McWhan, an owlish and witty 37-year-old in a shirt and tie, and six other club members. Most are in their 30s, and with the exception of Deirdre Rusling, all are men. A quick straw poll reveals that David Tennant is their favourite Doctor, with Peter Davidson a close second. They are mostly long-term followers of the show, and feel vindicated that what was once their somewhat shameful passion is now a critical and commercial success.

"Folk at work used to laugh at me because I liked Doctor Who," says Johnny Main, who has long hair, an Anthrax T-shirt, and works in the finance department of the Student Loans Company. "They thought I was weird. But now that it's back on TV, it has changed their perception of me. Everyone's watching it now. Doctor Who is Saturday night."

Glasgow Who and other superfans greatly appreciate the fact that between Doctor Who finishing in 1989 and returning to the BBC in 2008, enough time elapsed to allow the new generation of the show to be shaped by people who grew up watching the classic series. David Tennant, executive producer and lead writer Russell T Davies, and his incoming replacement Steven Moffat are all passionate aficionados who find themselves in the head-spinning position of making the show. For fans on the outside looking in, it feels like a victory for their loyalty during the wilderness years; they have stormed the citadel and are waving a giant stripy scarf from the top. As Alan Christison puts it, "David Tennant is one of us."

I ask the Glasgow Who group what it is they love about the show. The answers are varied: the British whimsy, the escapism, the Tardis. Everyone has their reasons. "I identify hugely with the Doctor and always have," says Rintu Basu, 46. "That character is outside of the human race. I was brought over to England from Calcutta when I was two years old and always felt a little outside the culture growing up in the south-east of England in the 1970s."

He laughs. "I'll tell you how strong the identification was. I remember as a 12-year-old looking in the mirror and suddenly realising I don't look like Jon Pertwee. Up until then, it hadn't occurred to me that I didn't."

Basu teaches communication skills, accelerated learning and hypnosis. "About 90% of what I talk about in the training room is related to Doctor Who," he says. He sometimes shows clips. Once, while working with a police force in England, he screened a Tom Baker monologue from the 1975 six-parter Genesis of the Daleks as a way into discussing the morality of policing. "Doctor Who has taken over my life and I'm quite happy about that," he grins.

Scott Linens, 39, puts his love of the show in simpler and oppositional terms. "Bugger Star Trek," he says. "Print that."

For as long as there has been Doctor Who there have been Doctor Who fans, which is to say people who aren't content merely to watch the programme but want to discuss it too. As soon as the first episode was broadcast, on November 23, 1963, people started recording the audio from the television with reel-to-reel tape recorders. And though it's hard to credit now, there was a time when William Hartnell, the stern, grandfatherish first Doctor, provoked the same sort of feverish excitement as David Tennant, the tenth Doctor, does now. People would write to the BBC production office to request signed photographs of Hartnell, and by the mid-1970s the newsletter of the Doctor Who Appreciation Society was giving away pin-up posters of the old gent. It's worth remembering, of course, that Doctor Who began in the same year as Beatlemania; the young people of Britain were ready to go bananas for new and exciting cultural products. Okay, the Doctor didn't wanna hold your hand, but he did seem keen on blowing your mind.

The difference between fandom then and now is technological. Doctor Who, with its rich history, huge level of detail, lost episodes and attractive modern stars is catnip for geekdom and exactly the sort of thing on which online discussion thrives. The enormous anticipation before each new series means that fan forums are always throbbing and wheezing with rumours, spoilers, leaks and long-lens photographs of night-shoots in disused quarries near Merthyr Tydfil. Most serious fans can't imagine getting through a day without logging on and catching up. As McWhan puts it, "There's more Doctor Who on the internet these days than there is porn. Which is quite disappointing."

It also seems to be true that the show now has more female fans. Partly this is thanks to David Tennant, who is to Sylvester McCoy what Hamlet is to Caliban, but it also has something to do with the way the female characters in the new series are written and perform. "Billie Piper was very much not a screamer, and I think that was brilliant for women everywhere," says Caroline Sinclair, 36, a fan from Cumbernauld. "All the companions in the old 1970s episodes were, like, 'Eek! There's a monster!' But Billie and Freema were more likely to rescue the Doctor. They were strong characters and I think that was very much what brought a lot of women back to it."

Sinclair loved Doctor Who as a child, but her interest waned in the late 1980s. She got back into it when the series returned with Christopher Eccleston as the Doctor. Her seven-year-old son, Scott, is autistic and she suffered from post-natal depression. Collecting autographs and other bits of Who paraphernalia is a hobby she can enjoy from home while looking after Scott, "and I suppose it is something that has created a special bond between us over the years as he has got older. We both have a passion for it and recognise the theme tune a mile away. We enjoy meeting actors from the series and love watching it together."

Both Sinclair and her son have been known to dress up as characters from the classic two-part episode The Empty Child/The Doctor Dances. This means she wears a nurse's outfit and a gas-mask. Her mother made the costume.

Colin Young, from the Midlothian mining village of Newtongrange, has gone to even greater lengths to demonstrate his devotion to the series. He has four tattoos on his arms and shoulders, and isn't shy about taking off his top and talking me through them. "Cyberman, Dalek, Timelord symbol, Menoptera. And that's my big fat belly."

Young is 41 "going on 12" and works as a cook at Liberton Hospital. His small flat has two rooms devoted to a vast collection of memorabilia, which includes a pinball machine, full-size replica Dalek, and the Servo Robot – a large prop from a Patrick Troughton-era episode. He reckons his collection is worth around 120,000, but that he shelled out about a quarter of that over the years. He frequently buys Doctor Who minutiae that would be of interest only to obsessive collectors. He is keen to find a Dalek Sugar Puffs box from the 1960s, and recently purchased some yellowing plans showing the lighting positions and set layout from the 1980 episode The Leisure Hive. "I have a compulsive nature," he admits. Young buys these things not because he particularly likes them but simply because they exist; he compares himself with George Mallory climbing Everest simply because it's there.

He has been a fan since he was six, and although he enjoys the new series, his preference is for the episodes from the 1960s. "It's annoying that it has become so popular," he says. "It used to be our own wee programme, but now everybody's blethering about it, and I'm like, 'No! It's my programme! Leave it alone!'"

Young reminds me of a Kennedy assassination conspiracist obsessively amassing evidence. But mostly he's an amiable guy. He considers himself a kind and helpful person, and wonders aloud whether it's because he has that personality that he can empathise with the Doctor, or whether liking the Doctor has made him kind and helpful. Whichever way it is, he is unembarrassed about being a middle-aged man in thrall to a children's television programme. In fact, he quotes Tom Baker's Doctor on the subject, and what he says would no doubt ring true for all Scotland's superfans: "What's the point of being grown up if you can't be childish sometimes?"

IT'S A dreich day in mid-March, 17 days until the long-awaited Doctor Who Exhibition opens at Kelvingrove, Glasgow, and the school groups touring the gallery and museum are finding it hard to concentrate on Egyptology. They're jumping up and down, vexing their teachers, and taking turns to peek through the letterbox that has been cut at kid height into the hoarding stretched across the front of the exhibition space. On the other side of the letterbox is a fearful stone angel, fangs bared, which will be familiar to anyone – almost seven million people – who saw the terrifying 2007 episode, Blink. The angel has been placed there by the exhibition designer, Stuart Wescombe, 36, who is keen to ramp up public excitement.

He seems to be achieving that. The opening weekend is already sold out, 1,400 tickets each day, and organisers expect that more than 200,000 people will attend over the course of the eight-month run. It is also hoped that David Tennant will make an appearance at some point. The exhibition is a showcase of creatures, props and costumes from the last four series of Doctor Who up to and including the most recent Christmas episode. It is hoped that after Planet of the Dead broadcasts next month the exhibition will include items from that episode. The largest of 100 objects on display is the Abzorbaloff, a creature played by Peter Kay in a 2006 episode. The smallest object is a sonic screwdriver. The Empress of the Racnoss, a giant red spider played by Sarah Parish, would have been on display, but at 4.2m tall was too large for the space.

There is still plenty to admire, though, including three interactive zones featuring Autons, Cybermen and Daleks firing lasers. With the exception of the Daleks, which are made by the BBC's art department, the monsters are created by Neill Gorton and his Millennium FX team at their prosthetics and animatronics workshop in Buckinghamshire. They have won several Baftas for their work on Doctor Who, and though it's a brilliant job to have, there's a lot of pressure too. Gorton, who is 39 and was inspired to get into his current line of work by his childhood love of the show, usually has a month to design and build each monster. Sometimes with complicated pieces like the Cybermen, each of which has 40 hand-made components, he gets a couple of weeks more.

"It starts with the script," says Gorton. "Invariably there's a description, and from there you extrapolate and push ideas. In the episode with Kylie Minogue, for example, there was a little guy called Bannakaffalatta, and it said in the script, 'He's three and a half foot tall and he's got a head like a conker. But red.' It's very simple to make a literal jump from that. With other things, there's a lot more design work."

Sketching is usually the first stage of the process, then Gorton and his team make a small clay maquette which they show to the production team. Sometimes their efforts can be so successful that they end up influencing the direction of the programme. "The Face of Boe started out as a throwaway line in the script – 'a five-foot face in a giant tank of gas'," Gorton says. "At the script meeting it was suggested that we could replace it with something that was cheaper to make as it wasn't important to the plot. But I loved the idea, and pushed to make sure the character lived. I showed Russell T Davies a drawing, he liked it, so we built it and everyone fell in love with it.The next minute he's being written into future episodes and becoming a pivotal character across two series."

The Face of Boe is already in place when I visit the exhibition. Like most of the other monsters, he is still covered in protective bubble-wrap, but someone has torn off a large strip from across the front of his tank, apparently so he can see out. It's fun to visit this work in progress. There are workmen drilling and hammering, and bits of Tardis lying around like flatpack furniture. Neen Wilder, a set painter from the series, is on secondment to the exhibition and is busy creating a marble effect using a swan's feather dipped in brown paint. Everywhere around are well-known figures from the series, wrapped in clear plastic, bound with tape, and piled up on top of each other. "It looks like a mass grave," observes Stuart Wescombe. "There's a Judoon but he's not got his head on yet, and I think that might be Kylie over there."

Wescombe walks me through the space, taking in the interactive sections, the display showing how the Ood heads (imagine a malevolent pickled onion chewing a pound of mince) were developed, and the part of the exhibition which recreates the Doctor Who art department in Cardiff, complete with storyboards, laptops and discarded sweetie wrappers. We stop for a while at the area where the Daleks will shout "Exterminate!" and fire their lasers, and pause, too, to admire the Moxx of Balhoon, a creature who resembles the offspring of Papa Smurf and the Mekon.

Some of the monsters are genuinely frightening. Think of those stone angels or the scarecrows in Family of Blood. So how does Neill Gorton know how far to push the fear factor? "There's no man in a grey suit from the BBC saying we cannot do this or that," he says. "Among ourselves we know what's right and what's wrong. We don't have blood, for example, or gore as such, because it is for a family audience. But at the same time you do want to be scary to a degree because that whole thing about hiding behind the sofa is so much at the heart of Doctor Who."

Stuart Wescombe understands this too. "The more crying children at the end of the exhibition the better," he jokes. "Then I'll know I've done my job."

• The Doctor Who Exhibition runs from this Saturday until January 4, 2010, at Kelvingrove Art Gallery and Museum, Glasgow. Tickets cost 7.50 (children and concessions 4.50); The Doctor Who Easter special, Planet of the Dead, will be on BBC1 on April 11