My very distant cousin Johnny Hallyday has been standing astride the French news for days.

TV news bulletins lead with the 63 year old "idol of the young," and serial murderer of every style of rock music since 1958. The front-page headline in Le Monde this weekend was "Le Cas Hallyday" - the Hallyday case.

President Jacques Chirac, a long-time friend of France's indestructible, "national" rock star, accuses Johnny of "uncitizen-like" behaviour."

Why the fuss? Johnny is leaving France. Or not quite. He plans to live for half of the year a few miles over the French border in the super-rich ghetto of Gstaad in tax friendly Switzerland.

That may not seem like news to you. Most popular entertainers live in tax exile.

Bien sûr, but Johnny is not just a popular entertainer. One cabinet minister described him last week as a "national treasure ... an important part of our heritage." Johnny de-camping to Switzerland for half the year is equivalent to the Louvre lending the Mona Lisa part-time to a gallery in Zermatt or half of the Eiffel tower being dismantled and re-assembled in Lausanne.

Johnny (pronounced Jo-neee) is an important political figure in France. He was attacked in his teens as a cultural leper, spreading diseased American values to French youth. He has, long since, become a symbol of French resistance to Anglo-saxon cultural imperialism.

He was for many years a backer of Mr Chirac and now - to Chirac's annoyance - endorses the man who expects to be the next centre right leader and president, Nicolas Sarkozy.

The Left is delighted. Look, they say, Johnny, the great patriot, the man proclaiming his confidence in a Sarko-led future, is fleeing the country.

The centre-right is trying to hit back. Look, they say, France is so over-taxed that even a generous, patriotic man like Johnny, who has financed half the French welfare state for decades, has finally had enough. If you elect Nicolas Sarkozy in the spring, no one in France will pay more than half their income in taxes.

Johnny Hallyday is France's best paid rock star (by far). He earns about €6m (£4m) a year but he gets to keep only about €2m.

Contrary to a widespread misconception, France does not have high income taxes. However, it does have crippling social security charges and an annual wealth tax on anyone with assets worth over €750,000 (including the family home). It is estimated that 10,000 wealthy French people live in tax exile.

Last year, Johnny applied for Belgian citizenship on the grounds that his father - whom he never met - was born in Belgium. Wicked rumour suggested that he wanted to be Belgian so that he could live tax-free in Monaco. French citizens who live in Monaco have to pay French tax. Belgians do not.

The citizenship committee of the Belgian parliament let it be known recently that they were inclined to refuse Johnny's application. Hence my distant cousin's sudden interest in Switzerland.

Why do I claim Johnny as a distant cousin? We are both half-Belgian. Johnny's father was called Smet. According to his French identity card, Johnny is still Jean-Philippe Smet.

My mother's maiden name was Desmet. That's close enough for me, even though Smet and Desmet are Belgian variants of "Smith".

A nun in the gym

Strangely enough, my last living Belgian relative recently emigrated from Belgium to France at the age of 86. My aunt was not fleeing into tax exile. She attracted no headlines. She has no income and few possessions. She is a nun and not even a singing nun.

Her religious order offered to move her to its new retirement and nursing home for elderly nuns and priests on a wooded ridge above Chambéry in the French Alps. Touchingly, she now lives next door to the building where she was first sent to train as a novice, aged 15, in the 1930s. Shades of The Sound of Music.

I visited her recently and was delighted to find her looking well. The retired priests and nuns had several activities on offer, including gymnastics classes. Did she go along? Yes, she said with a gently malicious smile, "to encourage the others".