Making fun of Mexico is okay, as long as it’s not aired in Mexico. The Mexican subsidiary of MTV decided recently not to broadcast an episode of South Park in which the president of Mexico, who resembled current leader Felipe Calderón but was not named as such, is portrayed as fiscally irresponsible and an international irritant.

MTV Mexico claimed its decision was based on the fact that Mexican law requires anyone broadcasting an image of the national flag to get permission from the government. But the network failed to do so and cancelled the “Pinewood Derby” episode to avoid being fined.

Fans of South Park and local bloggers suspected the real decision behind the cancellation was the unflattering portrayal of the president. But Mexico was not the only government made to look like greedy fools in the episode. At one point the world’s leaders agree to nuke Finland because it threatens to ruin an international scheme by which everyone profits.The broad white sands of Tiree, one of the most serene and beautiful sights in Britain, are being stolen by thieves to supply the building trade.

Environmentalists and local estate workers estimate that tonne upon tonne have been taken since Christmas, with contractors driving heavy vehicles down to the Hebridean sands under cover of night and loading up truckloads of the fine white grains, which are bagged and used by local construction companies.

The Isle of Tiree, a four-hour ferry ride from the mainland, is a place rich in tradition, and crofters among its 770 or so inhabitants have a legal right to take small amounts of sand for use on their land. But a building boom, fuelled by the island’s improbable status as a surfing destination, has led to much larger-scale exploitation, that could have devastating effects — Tiree is so low lying that it is known as the “land beneath the waves”.

Ross Lilley, an area officer for Scottish Natural Heritage (SNH), said the theft represented a long-term threat to beaches and to the island itself, if sea levels rose. “Heavy storms, like those of 2001, appear to be increasing and there is a long-term trend of sea levels rising,” he said.“We need to understand how vulnerable the coastline could be. It’s something the community has to protect because they are at risk from further erosion.”

Mr Lilley said that crofters play a vital part in the maintenance of Barrapol, a beach on the west of the island, that has been hit hard by the thefts.

Here, the sands are bordered by machair, a rich coastal grassland that helps to stabilise the sand deposits. The machair is in turn grazed and fertilised by the crofters’ animals, helping to maintain a delicate natural balance. “Sand and gravel in a place like Barrapol is moved around by the winds and the tides,” Mr Lilley said. “What [the thieves] are in danger of doing is weakening the cycle, by taking away so much sand.”