Get under the skin of football, my boss at The Football League decreed. So I did, literally. But after little more than a few seconds in the furry costume of "Beau Brummie", Birmingham City's Bulldog mascot, I was feeling hot, engulfed in an aroma that was not pleasant, disorientated and a bit alarmed. Please, boss, this is an assignment too far ...

Perhaps a minute passed and, as I wobbled around the commercial offices at St Andrew's, claustrophobia and a touch of nausea crept in as well. Where were my feet? Where was I treading? And through the tiny netting of Beau's "eyes", I couldn't see much, either; the walls were closing in on me. An horrendous case of "I'm A Journalist, Not A Canine ... Get Me Out Of Here!"

And I did, as quickly as possible. It was enough, too much. For the rest of the evening, as Birmingham took on Blackpool in the second leg of their Championship Play-Off semi-final, I allowed Beau to take back what was his right - the yellow leggings, white socks, boots, chest and arms, white shorts, extra padding, football shirt and, most importantly, his head.

Beau was welcome to it. And "Belle", his "lady friend", also. No way would I even consider a gender change and perhaps try on her even smaller and more restrictive attire. "Mr and Mrs Dog", as the pair are affectionately known, could do their own thing and I would simply observe, which I did. It was a fascinating and endearing insight into the world of a club mascot.

Initially, though, panic. The Beau and Belle costumes had gone missing, having been lent to the Birmingham City Ladies team. "I think they're in the cupboard," a voice said. Panic over. Out came the Beau and Belle heads from blue bags and, after the pathetic journo had fronted up, meekly walked the walk and miserably failed to talk the talk, on with their kit.

After some zipping up of each other, Belle - in her first season as Beau's sidekick, "he was a bit lonely," she explains - offers a complaint to the St Andrew's Fashion Police. "I don't like this neckpiece," she confides. "It looks like shoulder pads, which I hate." Horrible, also, when the weather is bad, when the costumes take on extra weight. It is lashing down outside; it is going to be a long, sodden night.

A certain mystique surrounds the mascots. They might have been "outed" in the local media in the past but it is preferable that they retain a semi-secretive aura. Much like Santa Claus; the youngest Birmingham fans must still believe. Thus, Beau, a 45-year-old full-time officer worker, and Belle, a 34-year-old part-time cleaner, like to lie low in their kennel.

"I've been doing this for 18 years," said Beau. "It gives you a great interaction with the supporters. Why do I do it? On the last away game of a season, you always go in fancy dress. One season, I went to Tranmere as "Mr Blobby". I got off the coach, I was walking down the road, and people were coming out of their houses to say 'Hello'. I got cries of 'Blobby, Blobby'.

"Next season, Blues were advertising for a mascot. I ummed and aahed about it - for about two seconds! - and got in touch with the club and said I'd love to do it. And it's gone on from there. I'm still waiting for my England call-up to perhaps go along to a game with their Three Lions.

"I've done it for so long, I might even follow the Beckhams and go to America and become Mickey Mouse. I'll have a bit of fun and you just don't know where it might all lead to." Belle intervenes. "Behave yourself," she chides. "OK, maybe Pluto," Beau replies. "At least he's a dog. But I've done it for so long here now, maybe I'm due a mascot testimonial!"

Doggy dreams, perhaps, but there are many perks to the job. As at the 2002 First Division Play-Off final at the Millennium Stadium in Cardiff, when Birmingham defeated Norwich City 4-2 on penalties after a 1-1 draw. "I'd done my bit and got changed out of my gear to watch the rest of the game," Beau recalled. "But I thought I'd better get back into it again and came out just as the shoot-out started. We won and I was celebrating with all the players on the pitch. It was great fun, a real laugh. I also got invited back to the team hotel afterwards and was able to take my family, which was nice, too."

And as at the 2011 Carling Cup final at Wembley, when Birmingham stunned Arsenal 2-1. "It was a fantastic experience, to go behind the scenes and see things that you wouldn't normally," Beau said. "We used a spare dressing-room, the size of which you could probably fit in a whole American Football team. It was massive. And we were looked after really well."

Birmingham Mascot

To work. Beau and Belle trundle out of the commercial offices, down the stairs - exchanging high-fives with the stewards along the way - and into the teeth of the monsoon. Then under the Gil Merrick Stand, which houses the already noisy Blackpool fans, and to the Mascot Lounge, where the young matchday mascots are eating and being entertained.

Gillian, the Head of Safeguarding, ushers Beau and Belle into the room to present prizes to the excited youngsters and then Roy, the club photographer, takes snaps of Mr and Mrs Dog, the mini-mascots - seven for Birmingham, one from Blackpool - and their parents. Smiley pics for the family albums. As the Blackpool players file past, on their way out to warm up, each gets a high-five from Belle.

At 7.10pm, it's time for the pre-match walkabout. B&B wander around the pitch, posing for more photos with any Blues youngster who wants one. And many do. But no talking to them, no conversations. "It's just not something you do," Beau said. "I suppose it's about keeping up the illusion. We're all action, no chatting. A lot of what we do is common sense, just doing the right thing at the right time."

Ten minutes later, Gillian shepherds the eight mascots from their lounge to pitchside also. Beau and Belle join them and kick around a football, Beau jigging to some Ibiza-style anthem blaring over the PA. More happy snaps and the rain has relented. A little bit.

As kick-off nears and the expectation among the crowd intensifies, Mr and Mrs D go over to the main players' tunnel at the opposite side of the Gil Merrick Stand. "Mr Blue Sky", the Electric Light Orchestra classic, gets the home supporters rocking and Beau indulges in a touch of air guitar to ramp up the volume further. He also conducts a rendition of "Keep Right On To The End Of The Road", the traditional song of the "Bluenose" masses.

Beau is far enough away, sensibly, from the Blackpool fans. No need to inflame them. "I do remember a match here," he reflected later, "in the days of terracing, when some of the away fans were leaning over the top of the fence and wanting to shake my hand. I put my hand up but a few of them grabbed my arm and tried to pull me up and over the fence. I got rescued by one of the stewards pulling me back down but it was a close call."

The teams appear. More photos, this time in the centre circle, with the mascots and match officials. At 7.45pm, with Birmingham trailing 1-0 from the first leg, referee Chris Foy starts the game. Beau and Belle return to the Mascot Lounge, in which they will watch the match on television. As they remove their heads, their hair is drenched in sweat. "But it's so much fun out there tonight," Belle says. "It's an amazing crowd, they're so up for it."

Give the dogs a bone? Er, not quite. The Bulldogs tuck in to lasagne, potato wedges, salad and fresh fruit - from a plate, not a bowl! - and recharge their batteries for the half-time show. Its main feature is the "Chip and Win" competition, with fans winning prizes if they can strike the ball into the net, without it bouncing, from various distances.

It helped Blues - along with the other contributions of their mascots and their PA and big-screen entertainment - to gain the "If The Football Doesn't Entertain You, Then This Will" award from The Football League this season. "It's nice to get a bit of recognition," Beau said. "Out of all the clubs, ours was picked out as deserving of the award. That's great."

There is no sound on the TV, just the cheering, the rumble, of the Blackpool fans above the lounge to listen to. Marlon King hits the crossbar for Birmingham. "Oh dear, I should have patted him on the back before kick-off," Belle says. "Every time I do that, he scores!" Pats on the back, too, for B&B's work in the wider Brummie community and beyond.

"As well as the Blues functions, we go to a lot of events - open days, mascot races, fund-raisers, children's charities," Beau explains. "I won the Mascot Olympics at Huntingdon in its first year. And there's also a mascot website; we all get together sometimes. We do get asked to go to a lot of places, especially since Belle arrived, and it's just a question of how many we can fit in. We do as much as we can do."

Now and again, Beau and Belle double up for mascoting duties with Birmingham Ladies. And Beau has done a bit of moonlighting, too, with the Warwickshire Bears cricket team at Edgbaston. First as Carmen the Bear, then as Hugh the Bear. Not to mention his TV appearances with Ant and Dec - "They signed my shirt, they were great" - and on a John Motson tribute programme.

It's almost half-time and it's dog-eat-dog out there as the teams slug it out in the incessant downpour. B&B set forth, soon to be soggy pooches again, as Stephen Dobbie increases Blackpool's aggregate lead to 2-0 in the 45th minute. The ceiling and door of the Mascot Lounge shake as the Tangerine rumble above explodes in celebration.

A Birmingham flag bearing the legend "Joys and Sorrows" hangs limply from the top tier of the Gil Merrick. And further bad news. Chip and Win is cancelled because of the weather. But Beau and Belle, in the eye of the storm on the pitch, still accept their Football League award. Then that's it, their job is done. Off to change, back to reality. It's a dog's life, indeed, but no more this evening.

Mr and Mrs D, now in civvies, return to the Mascot Lounge. Matt Phillips has extended Blackpool's lead to 2-0 on the night and 3-0 overall. When that goal went in, it felt as if the lounge ceiling was going to collapse. Amid his misery at the scoreline, Beau reveals that he was once almost poached by Aston Villa, Birmingham's great rivals. "I was asked if I wanted to do it," he says, "but immediately said 'No thank you very much'. I'm a Bluenose through and through and I put my heart and soul into this job. It just wouldn't have been right at all. It was beyond my thinking."

Beyond rational thinking, maybe, that Blues could peg back Blackpool. But Nikola Zigic and Curtis Davies reduce the gap to just one goal on aggregate. "Come on, boys," Beau urges. "We can do this. We're going to do this." Yet they couldn't, they didn't. No Wembley final this year.

Beau Brummie sits in silence, arms crossed, staring at the TV screen. Little from Belle, either. They are disappointed, in despair, devastated. Perhaps even dog-tired. But they'll be back next season, doing what they do best. In their own inimitable way, week-in and week-out, getting under the skin of football.