Thousands of men each year will be asked to be a best man. Many will relish the opportunity to humiliate the groom publicly; others will be terrified, particularly if, like me, they suffer from a phobia of public speaking.

I was filled with pride and dread in almost equal measure when I was asked three months ago to be a best man. But the prospect of speaking before 50 strangers, with the added expectation of humour, mostly made me feel sick. Glossophobia is the popular term for speaking anxiety and aptly derives its name from the Ancient Greek meaning, literally, “tongue fear”. An astonishing 75 per cent of us are estimated to suffer in varying degrees.

I'm 28 and had my first panic attack before a presentation at university seven years ago, subsequently (and embarrassingly) passing out. Since then I have managed to avoid a repeat performance through a combination of skilful deflection and, on occasion, barefaced lying.

Borrowing the tools of the acting trade

In an attempt to learn how to rein in my anxiety, I took my actor partner's advice that I borrow some of the tools of his trade and booked myself on to a Performance in Presentation course at the Central School of Speech and Drama in London with Caroline Goyder, an actress and voice coach. “Fear switches off the brain,” she says. “What actors learn is to breathe through fear, see nerves as a good thing and surf them.” It's a skill that I have found to be elusive.

I had three hour-long sessions at two-week intervals with Goyder, attending the final session a day before the wedding. She has worked as a voice coach for six years, with clients ranging from TV presenters to big business hotshots and, I notice, never uses “ums”, “ahs” or “ers” in her speech.

But she is fond of using diagrams to illustrate exercises and, in our first classroom session, introduces the skills I will be learning by drawing out a Venn diagram of brightly coloured overlapping circles dedicated to voice, movement and acting. Over our sessions, she cherry-picks exercises from the overlaps, covering “grounding”, breathing, posture, body language, stage craft and voice.

“Grounding” is a trick actors use to lower their breathing and relax their shoulders to keep their energy levels low. “You've got to get really heavy and imagine that you've got lead in your boots,” says Goyder. This counteracts the biological maelstrom and upward rush of energy that follows a panic attack.

You have to bend your knees gently and do basic exercises to relax your shoulders, neck, jaw and face, which all hold tension when you are under stress. You then focus on breathing from your diaphragm which, Goyder says, is key to managing nerves. Our largely sedentary lifestyles mean that most of us “chest breathe”, relying on the muscles of our ribcage to draw air into our lungs instead of breathing using our diaphragm.

“If you breathe high,” Goyder says, “it takes your chest and shoulders into stress and the body prepares itself for fight or flight. That diverts blood away from the front of your brain to your heart and limbs and stops you thinking, so you end up tongue-tied in front of an audience. That's why actors spend so much time learning to breathe.” She encouraged me to imagine roots dropping down from my feet into the floor, while relaxing my knees and pressing my big toes into imaginary sand. When she then tried to push me over, my feet felt like they were nailed to the floor.

Wedding guests want to be entertained

Goyder says that the best man's speech should not be too “cerebral” and should be closer in style to stand-up comedy than a business presentation. Nevertheless, she believes that the way you deliver the speech, rather than what is in it, has the most impact.

This is backed up by Albert Mehrabian, a Californian psychology academic. In his book Silent Messages, he says that there are three elements in any face-to-face communication - words, voice and body language - which all account in different measures for how much we can win over an audience. According to Mehrabian, content is responsible for only 7 per cent of the message; body language and voice tone make up the rest.

As I work with words for a living, my instinct was to present the speech word-perfect, something that Goyder discouraged, dubbing it as like a “head boy”. She says: “What's really important is not to get stuck on the paper. The written word and spoken word are not the same thing. Wedding guests are not looking for a toastmaster; they want to be entertained.”

She also encouraged me to make constant eye contact with the audience; she calls this “sending out a present” to guests. I spent half a session addressing photographs of my “bridesmaids” - Jennifer Saunders and Natasha Richardson, former students at the Central School of Speech and Drama - which initially felt ridiculous. But putting the focus on the audience stops you feeling self-conscious.

Goyder also advises using big gestures, beginning the speech with your arms stretched open and your palms facing upwards. It feels exaggerated at first, but making yourself physically big makes you feel more confident. She says that you should also pause a lot, giving yourself time to think. “Slow down when you get nervous and use the pause to cut out the ‘ums' and ‘ahs',” Goyder says.

Putting all these skills together was rather like learning to drive. I would remember to breathe from my diaphragm but then forget to make big gestures, or I would make eye contact but neglect to pause.

However, during my final session Goyder encouraged me to concentrate on having fun without worrying about what I had and hadn't remembered. It was also the last time I practised my speech as she was keen for me to be focused on the audience. She even let me go to the pub the night before.

When the big day arrived, my nerves set in only as we sat down for the wedding breakfast, a situation not helped by children hiding my prompt cards. Towards the end of the groom's speech I felt no more than a creeping dread, instead of the spasms of panic that had gripped me weeks before.

The two tools from Goyder's “confidence toolkit” that I found most useful were concentrating on breathing properly and absorbing myself in the groom's speech. The moment when I stood up to speak seemed to last only seconds before it felt like someone else had taken over and that I was a member of the audience. My ad-libbing got the most laughs, probably because they were moments of spontaneous humour.

The elation I felt afterwards lasted all day, not only because I did something that I thought I was incapable of, but also because of the number of people who said how much they enjoyed my speech.

But the most gratifying thing was how proud Neal, the groom, was of my performance. And I didn't even have to make a cheap crack about the mother-in-law.

For more information call 020-7559 3954; visit www.cssd.ac.uk . The performance in presentation course costs £500