Pierre Gruneberg, who has died aged 92, fled Nazi Germany as a boy and went on to enjoy a gilded life as resident swimming coach of the Grand-Hôtel du Cap-Ferrat for 70 years, becoming the instructor of choice for aquaphobic celebrities and billionaires.

The pupils he oversaw in his cliff-edge pool on the French Riviera ranged from Charlie Chaplin and Somerset Maugham to Aristotle Onassis and Mark Zuckerberg by way of Tina Turner, Brigitte Bardot, David Niven, Roger Moore, Elizabeth Taylor and Bono.

It was Gruneberg’s boast that he could teach anybody to swim, no matter how trepidatious. He emphasised that confidence in the water came from learning to breathe correctly, and to this end taught what he called la méthode de Gruneberg, which he had devised in 1953.

Pupils would initially be instructed in strengthening their breath hold by sucking at a ping-pong ball through a length of hosepipe, before being presented with a salad bowl full of water in which they would dunk their heads and practise breathing gently out through the nose: “The nose, you see, is the chef l’orchestre of this symphony of breathing in the water.” Only then would the students enter the pool, and in most cases were ready to brave the Mediterranean within a few hours.

His patience and ingenuity were a match even for those who were truly terrified of water, such as the designer Domenico Dolce. “I started by putting a drop on my finger and rubbing it on his nose. It took two or three hours before we could use the salad bowl. By the end he was jumping in the pool.”

Gruneberg was attentive to the whims of his glittering clientele, recalling that he had to swim in circles round Paul McCartney when the ex-Beatle went into the sea, to keep a watch for jellyfish; he did the same for Robin Williams, whose aversion was to sharks. He was particularly pleased to have helped Kristin Otto, who had six Olympic gold medals for swimming but was terrified of the open sea.

Gruneberg owed much of his success to a genial, reassuring manner that made pupils trust him even while he kept one foot unceremoniously on their backs to keep them underwater.

“If he wasn’t doing this he’d be a psychologist,” observed his wife Doreen. “He knows how to unlock your fears one by one – he has the key and you’re the door.” The celebrity he most regretted not meeting was Woody Allen: “I like the idea of teaching people with a problem. I have seen his films and I think he is packed with problems.”

He would relax his pupils before lessons began by showing them his livre d’or, or scrapbook. It contained a drawing of Gruneberg by Jean Cocteau, a sketch given to him by Picasso reckoned to be worth tens of thousands of euros, and a cartoon of a Russian being forcibly submerged in the salad bowl, drawn by Cabu shortly before he was murdered in the Charlie Hebdo terrorist attacks.

Gruneberg spent his summers on the Riviera and in the winter worked as a ski guide in Courchevel, continuing in both jobs until he was 90. He was also a professional physiotherapist and masseur, serving in that role with the French contingent at the 1956 Melbourne Olympics. Among those he could claim to have pummelled were Elton John and George HW Bush.

He did his best to remain unimpressed by his more famous clients, observing that “every man is created equal when he’s wearing nothing but his swimming trunks.” One of his most memorable pupils, he recalled, was a former SS officer who had no idea that most of Gruneberg’s relatives had perished in Auschwitz; Gruneberg later admitted that when the man complained of loneliness, with most of his comrades having died in Russia, he quietly rejoiced.

Peter Grüneberg was born into a German Jewish family in Cologne on March 6 1931; his father was a lawyer and his mother a teacher. In the mid-1930s his older brother won a race at school, only for fellow pupils, members of the Hitler Youth, to throw stones at him and demand he be disqualified as a Jew.

Their mother promptly took the children to live in Paris. Pierre’s father initially thought this an over-reaction and stayed behind, but later hurriedly joined them.

Upon the German invasion, the Grünebergs buried their nest egg of gold coins under a cherry tree and fled south on forged identity papers. Peter was reinvented as a French boy, Pierre Gerard (later, when he reverted to his original surname, the umlaut was dropped).

Aged 12, he used to sit within earshot of occupying German soldiers, listening to their sexual boasts: “I understood every word but I had to make out I didn’t. It was a dangerous game but I just couldn’t help doing it.” At the end of the War the family returned to Paris to find their supply of gold undisturbed.

In 1950, after taking his swimming coach exams, the 19-year-old Pierre hitchhiked from Paris to the Riviera. He searched for a hotel that had a pool – “I didn’t want to spend my days waist deep in the sea” – and pitched up at the Grand-Hôtel, where the manager, André Voyenne, agreed to give him an interview.

At one point Voyenne showed him a picture of four beautiful girls and asked him what he thought of them. “I knew without a doubt that however I answered that question would decide my fate. Nervous, I replied, ‘Listen, I came here to work, not to chase girls.’ Within a week I had a signed contract.”

In the 1980s he began to spend part of the year touring upmarket hotels in Britain offering swimming classes, which led to a considerable boost in his international reputation, aided by his status as a link with the lost glamour of the post-war Côte d’Azur. He published several manuals on swimming and ski-ing.

Gruneberg, who was usually seen sporting one of a distinctive array of conical straw hats, owned two battered Citroën 2CVs – “the greatest treat I can give famous people is a ride in a deux-chevaux. Bryan Adams was absolutely thrilled” – although visiting journalists found his driving more haphazard than his swimming.

Despite his good looks and charm, Gruneberg claimed to be too shy to approach women at his own initiative, and got to know both of his wives through teaching them swimming. He married first, in 1990, Silvia Monfort, one of France’s great classical actresses, who had been his partner since the 1960s; she died in 1991 and her correspondence with him was later collected as a book, Letters to Pierre.

He married secondly, in 2012, the British singer Doreen Chanter, of the 1970s duo the Chanter Sisters. She survives him.

Pierre Gruneberg, born March 6 1931, died June 4 2023