Look out - she's behind you!

Standing on the steps leading to the dressing rooms of Hackney Empire, where Cinderella has been playing for the last three days, Carl Parris's face drops. He has just been told by director Susie McKenna that I am to play the back end of the pantomime horse tonight. Carl is the front end. It's two hours before the curtain goes up. The 28-year-old dancer feigns a smile.

He's not the only one who's nervous. Despite being compared to the back end of a bus often enough, this, I fear, is another kettle of fish. Susie takes me onto the stage. On one side is a golden carriage in the shape of pumpkin. Cinderella's broom is leaning against a wall. ``Clapton, the pantomime horse, is the most important person in the show,'' announces the 35-year-old from Hackney, who also plays Prince Charming's thigh-slapping manservant. ``He provides one of the first big moments of comedy in the show, so it's important that we grab the children as soon as possible. That first entrance with Clapton is pivotal to the rest of the show.''

If that isn't enough to make me want to bolt, I'm informed that Prince Charles and Jerry Hall were in the audience earlier in the week. Susie produces a video camera and shows me a tape of the show with Clapton's entrances and exits. ``Basically anything Carl does you have to mirror,'' she says. I ask what the worst thing is I can do. ``Show any piece of yourself outside the costume, because the reality will be blown.''

Any chance that Carl might go in one direction and I go in another? ``That's possible, too. So that's pretty much of a no-no really. As long as you keep looking at his feet you should be all right.''

I'm told that dancer Jason Parmenter will be playing one of Clapton's scenes, as it's too tricky for a novice. I'm suddenly struck by a dreadful thought. ``How many pairs of back legs are there?'' I ask.

``One. You'll have to take them off for Jason,'' says Susie.

``Will I be standing in the wings in my underpants?'' I ask, horrified.

``I'm afraid you might have to be, yes. But we're theatre people, you know, we're used to people showing their bits.'' Luckily, I'm wearing a sensible bra.

Carl, in his fifth panto this year, appears for a quick run through. This is his first and last time as a horse, he says. ``It's really gruelling. You look at it and think `that's a bit of fun', but when you're inside there's no ventilation. It's like a sauna.''

How does he feel about my being his rear end tonight? ``I just hope you can keep up,'' he says.

I put on the brown furry trousers, which come complete with feet, and slither headfirst into the back of the costume. ``Try and fill the horse out, otherwise it will sag in the middle,'' says Carl. I wiggle backwards.

Jason, 28, from London, who plays Clapton's rear end on alternative nights, says he is delighted I am relieving him of two scenes tonight. ``It was funny when I did it the first time, but it's wearing totally thin now. It's very hot. And it's very smelly - not because of Carl, it's an old costume.'' The smell factor is frankly good news, as I am already a bit wiffy myself from anxiety.

In the male dancers' dressing room a fantastic array of underwear has been on display. It's only minutes before the show starts. ``Shouldn't we be downstairs by now?'' I ask, getting damper under the armpits by the minute. Someone explains that the Tannoy isn't working and they can't hear the calls.

We troop down to the stage. Waiting in the wings, my view is suddenly obscured by an enormous pair of breasts. They are caught in the sort of bra that would keep an entire herd of wildebeest still. They belong to Tony Whittle, who is playing an ugly sister. His blue sweeps of eye-shadow override his eyebrows. ``You've got a lovely rump,'' he notes.

There's a whiff of perfume. It's the Wicked Countess, former EastEnder actress Carol Harrison, who played Tiffany's mother, Louise, sporting a blond shoulder-length wig, black tailored suit, black pill-box hat and heels.

I break the news of my starring role. She appears unfazed by the competition, pats me on my furry behind, and says: ``Break a leg, darling.'' I may well do.

I'm told to stand back as the scenery is about to move. It's time for our first scene. I climb into the back of the costume and grab onto Carl's belt. Keeping my head down and back flat, so as not to look like a camel, we gallop off onto the stage. Buttons, alias former EastEnder Richard Elis, who played squatter Huw Edwards, is holding onto the tail.

I'm having trouble seeing Carl's feet. With my head so far down I'm having to peer over the top of my glasses. Everything's a blur. My hair falls over my eyes, and all I see is two blond curtains. I suddenly realise Carl has executed his first kick. I kick too, hoping no-one notices it coming five seconds late. We then skid around a corner like a car, before charging offstage and depositing Buttons. Again, I fear I'm a little late with my leg work.

Once offstage I whip off Clapton's legs and hand them to Jason. I tug my T-shirt down over my knickers, silently thanking God that I had the foresight this morning to avoid the pair with the holes.

It's almost time for the slapstick scene. Jason, who has just finished his scene, hands me back Clapton's legs, and Carl frog marches me to the correct side of the stage. Buttons is to grind pepper over Clapton's nose, he sneezes and the resulting snot is collected for a face pack for the ugly sisters. Carl and I trot onto the side of the stage. I find myself looking at the orchestra through Carl's crotch. I suddenly worry about looking like a camel and lower my head. My neck starts to ache. Ugly sister Tony Whittle is ad-libbing. ``There's something not right with that horse,'' he says, to squeals of laughter from the audience. I rub one of my legs against the other for dramatic effect. It's time to hare off again around the stage and exit. I'm having a fabulous time.

My moment de gloire over, I ask how I've done. ``Brilliant,'' says Richard Elis. ``You cocked your leg extremely well,'' says Norman Bowman, who plays Prince Charming. ``I thought you were superb, darling, I thought it was a water-shed actually,'' enthuses Carol. In her dressing room, a sarong covering her underwear, director Susie joins in the chorus of approval. ``You were fabulous, a star in the making.''

With such talent, it's clearly time for a career change. Back of a panto horse this year, sharing the stage with Dame Judi the next. I start mentally composing my letter of resignation to The Independent's editor.

``Do you think I'm a natural?'' I inquire of Susie. ``Um, maybe just for the horse,'' she says, diplomatically. It wasn't what I was hoping to hear.

`Cinderella' plays at the Hackney Empire until 9 January. Box office: 0181-985 2424