Yet the company he travelled with, Eurocamp, says the regulations are not so obscure after all. On page 27 of its Traveller's Guide to France, squeezed between Organised Games and Other Activities, is a paragraph about the loi.
"Water purity regulations insist that camp sites forbid the wearing of shorts-style swimming trunks (only 'brief' style trunks are allowed)." The illustration (below) makes the point succinctly.
Pity the poor traveller arriving by Eurostar at Waterloo, and hoping to continue the journey by Tube. Anyone who wants to reach the rail termini of Paddington or Marylebone, or pop along to Piccadilly or Oxford Circus for shopping or sightseeing, faces big problems for the next eight months.
From midnight tonight, no trains will run on the Bakerloo Line south of Piccadilly Circus because of engineering works. Dismal news for the capital's commuters. But for travellers unfamiliar with London's transport, it promises to be truly bewildering.
Suppose you want to reach Oxford Circus. The Underground offers several suggestions. First, take an ordinary train back down the railway to Vauxhall and change to the Victoria Line - an obstacle course unsuitable for anyone carrying more than a briefcase. Better catch the "Bakerloo bus" that is replacing the Tube. The problem here is that first you have to find your way to the Underground booking hall and buy a ticket, then return above ground and locate the bus. If instead you find, say, the 176 bus stop and spot a regular bus to Oxford Circus, you must either throw away your newly acquired ticket and buy another one - or risk a pounds 5 fine.
Seven years ago this morning, the Berlin Wall fell; and 24 hours ago I met the unfortunate winner of the competition to celebrate 10 years of the Independent Traveller.
The prize, to use the term loosely, is a trip to East Berlin by independent and economic means, ie mostly hitch-hiking. But even before our planned journey to Berlin began, things went badly wrong. On Wednesday morning I went to the German tourist board in London, only to find that the office does not open until an unGermanic 12 noon. The maps that were promised had not arrived by the time I left, clutching only 1976 autobahn map.
The trip was to have begun with a rail/ship crossing as far as the German border. Sadly, when I tried to book the cheap pounds 49 ticket all the seats were full. The next fare up was more expensive than flying - at least to Holland. So we began by flying from London City airport to Rotterdam. The winner, Alison Clements of Maidstone, bravely turned up at the airport despite a fear of flying. I also learned that she has never hitch-hiked before, even though we face a 400-mile hike across northern Europe.
Our reports on the ordeal - sorry, adventure - will appear next Saturday. I suspect that they may conflict.