Small wonder: How Thomas Quasthoff sang his way into the big time

Thomas Quasthoff loathes newspaper clichés, and his fuse is short, so woe betide any journalist coming out with stuff about the "tiny, deformed figure with the huge voice", who has "courageously sung his way to the top of the world". It's not that these phrases contain lies, because every word is true; what he can't abide is the patronising tone in which they are delivered. This 48-year-old German baritone – whose stellar performances in both classical music and jazz are routinely greeted with awards and packed houses – demands to be seen, quite simply, as an artist.

He has stipulated that our interview should take place in his favourite Berlin restaurant, next door to the conservatoire where he is a professor. His smile welcomes me from a corner table, and it's not his diminutive size I register, but the attractive masculinity. His wife will be along in a while, he says, but in the meantime he wants to tell me about the international song competition he's just set up. "We Germans have the greatest song-poets in the world, yet we've never had a competition to reflect it," he says combatively. "If you know any brilliant young singers, please tell them to enter – there are still a few days before the deadline." In his view every Lied – Germany's song-form – contains within itself a small opera, and when you listen to Quasthoff singing Schubert's songs about love and death, abduction and betrayal, you realise he's not exaggerating. His lightly accented English is near-perfect, and delivered with easy grace.

Rather than giving my thumbnail sketch of the man now facing me, let him do it. This is how he perceives himself, perched on a high stool to look in a mirror before going on stage, in his aptly titled memoir The Voice: "A four-foot-three-inch concert singer without knee joints, arms, or upper thighs, with only four fingers on the right hand and three on the left. He has a receding hairline, a blond pig head, a few too many pounds around the hips, and he's in a superb mood." That's pretty much what I see, including the mood: the flippers with fingers attached are so short that he has to lean over awkwardly to cut his food, as do others impaired by thalidomide (a drug that, when used by pregnant women in the 1960s, caused abnormalities in developing foetuses).

But since this very private man has expressed a willingness to talk about his life, I ask for his earliest memory. "Watching my mother, father and brother watching me through a glass window. It sounds now as if the clinic was cruel, but the problem was they didn't know how to help people like me – they didn't want to make a mistake, so I was over-protected. I was kept in an isolation ward, in a full body-cast, for my first 18 months, and people weren't allowed in for fear of infection. It was not a normal childhood." You can say that again.

Home (near Hanover) – once the clinic finally allowed him out, "looking like a little seal" – was a happy place. He hadn't been expected ever to walk, but his resourceful parents devised means to make him do so. His father invented a rail-and-clamp device, and the three-year-old collected copious bruises trying to walk with it. His mother discovered that by rewarding him with chocolate for each step he took, he could learn like a Pavlov dog. They also sang to him, and he sang back: light ballads with his mother, Verdi and Beethoven with his father, while his elder brother Micha (who later assisted in the writing of The Voice) initiated him into jazz and rock. And it quickly became clear his voice was special.

When did he realise it would be his career? "When I won a big competition at 24. Until then there were always reasons why it couldn't happen, even though I wanted it to, and they were all to do with my disability. It was always: I would love to do it, but I cannot. I had won two smaller competitions, but even then I didn't know how I could actually live from this profession. Only at 24 was the rocket launched into the universe."

Considering what happened to him at six, it is a miracle there was a rocket at all. Though his parents wanted a normal education for him, he was rejected by school after school: "The message was always: cripples aren't welcome – they belong in a special school." That's what happened, but the boarding school to which he was sent sounds like Dotheboys Hall. Some of his new friends had been thalidomide babies like him, "others were demented children, or Down's syndrome children, or epileptics, or autistic".

And they were all in the care of a woman teacher with a sadistic penchant: 24 hours without food and gargling with saltwater were her usual punishments. Favoured miscreants – Quasthoff was one – were strapped into their beds at night, left in a freezing corridor, and hidden in a cupboard full of used urine bottles if a doctor came by; sleep deprivation was another part of this maltreatment. One day his best friend, Tim, was found dead in his bed by the teacher on her early morning rounds: "When I asked what happened, she simply said, 'He passed.'" When he tried to ask more, she told him to shut up and get dressed for breakfast.

These scenes could have come straight out of Dickens: has he read Nicholas Nickleby? "No. To be honest, if you've been through these things, you don't need to read about them as well." Finally rescued by his parents, and accepted by a more enlightened establishment, he learnt to fight his corner. As "a dwarf without arms stalking across the playground on stilts" he was cruelly teased, "though my big mouth gradually won me respect".

But he had continually to contend with the unkindness of strangers: seeing people in his ultra-Catholic home town cross themselves fearfully as he passed in the street; ' discovering he couldn't join his classmates on a trip to Finland because none of them – not even a teacher – would take responsibility for looking after him. It took him a long time, he says, to recover from this latter humiliation. Being turned down by the Hanover conservatoire because he didn't have an additional pianistic qualification – how could he have played the piano? – was another blow, and precipitated a deep depression.

"All teenagers get depressed," he says philosophically. "But yes, all my friends got girlfriends, and I didn't, which was not nice." (In his memoir he's more explicit about this: "I catch myself standing before the tall mirror in the hallway thinking: No girl will ever hold hands with you – you don't even have hands. Nor real legs. You are ugly. You are small. You are a crippled gnome.") "And then I felt such a loser because I couldn't study music as I wanted." Being the popular classroom clown was not sufficient: he gave up studying, took to drink, and one cold November night simply ran away, to be found by the Red Cross, shivering in a ditch.

Then music – plus his indomitable will – took over. His father found him a singing teacher, and he quickly blossomed as an all-round exponent of everything from Donizetti to Louis Armstrong, Stevie Wonder to rock'n'roll. Believing music would have to remain a private passion, he started studying law, but simultaneously began performing with his brother in church halls and jazz clubs, and after a couple of years realised he could, and would, make his living as a singer (he also developed a parallel career in satirical comedy).

At this point his wife Claudia, a graceful thirtysomething, joins us at the table, and her part in this story brings it forward two decades. How did they meet? She was editing a TV talk show to celebrate his second Grammy award, she replies, and needed some basic information from him on the phone: "And to my surprise, our conversation lasted two hours." To which Quasthoff adds: "I liked her voice, and that she was so honest. Then I met her, and boom! A shock. I was in love." He'd had other relationships, but wasn't in one at the time: "She wrote to me, and we met." Claudia: "I was very impressed by him, by the energy, and way he handled things. The physical thing didn't matter at all, and it doesn't now – he's just shorter, nothing else. I just thanked him for meeting me. But then we started writing emails and phoning, then he invited himself to my birthday party – and that was it." Quasthoff: "Since that day, four-and-a-half years ago, we are together."

In his memoir, Quasthoff talks of throwing off "the burden of sympathy", and mercilessly mocks his appearance, likening himself to the hunchback of Notre Dame. Was that self-administered therapy? He laughs: "Yeah, well, just look at me! If you don't maintain a little distance from yourself in this kind of thing, then something is wrong. If I can't laugh about myself, I'm lost."

Then he tells of buying a jar of cooked potatoes, trying to open it first with his hands, then with a knife: "I worked so hard on it that after wrestling for half an hour I was drenched with sweat, and I started to laugh – it was just so funny. Claudia and I make fun of these little misfortunes all the time. It's like when I was in school and the maths teacher said 'It's as easy as counting on your 10 fingers – oh, Thomas, I'm sorry.' And I replied, 'That must be why I'm so bad a mathematics – I have only seven.'"

When I say his book is strengthened by this humour, he asks what its chances are of being published in Britain. At my prediction that it not only ought to be published but also acclaimed, he looks surprised and pleased.

Though he may have fronted concerts to raise cash for medical equipment for the children of Chernobyl, Quasthoff resents being held up as a role model for disabled people. If his book has an inspirational function, he says, it should be for the ordinary millions whose disabilities are less visible: "No matter how bad life seems, there is always a chance to do something well, to find a way to make yourself happy."

Does he feel anger towards the pharmaceutical company that marketed thalidomide, and is still doing so around the world – modified by a caution about taking it in pregnancy – today? "How would my anger help? Would it change my disability? No. Would it force the company to pay more in compensation? No."

Money he has, thanks to his dizzy stage career and his records, among which Thomas Quasthoff: The Jazz Album, which has outsold all the rest put together, looms large. Deutsche Grammophon took a lot of persuading that their star classical singer could cut it with Gershwin, Ellington and Stevie Wonder, but his innate swing carried the day. He's made two successful forays into opera, but doesn't want to put himself through that again: "It seems an unnecessary display of my disability." His proper place is on the recital platform, and nowhere more happily than in his beloved Wigmore Hall: "With an audience which has been long-time-grown. That for me is ideal, and it's all I ask for."

It is 2.30pm: time to go back to his students, of whom he's ferociously demanding. "You have to make it very clear that even to live from this profession – let alone have a career – is getting more difficult all the time. You can count on one hand the German singers who can live from doing concerts." (And for that, one of Quasthoff's extremities would probably do.) Then he wraps things up with a triumphant coda: "Everything in my life has been unexpected. The University of Hanover rejected me; now I have a life professorship in Berlin. And I am so happy with my family. If you had told me 20 years ago that all this would happen, I would have replied, 'Oh yeah?'" And he saunters briskly out.

Thomas Quasthoff sings at Wigmore Hall, London W1 (020 7258 8200) on 21 November, and will be the Barbican's artist in focus for five concerts from 10 January 2009 under the title Die Stimme (The Voice). The closing date for entries to the Lied International Song Competition is Friday; information from info@das-lied.com