Surprisingly, the luxury-goods business is having a strong year, largely thanks to demand in China, the Gulf and other emerging economies. (Indeed, things have been so good that perfume-makers face a new product-liability problem in Russia, where oligarchs' girlfriends buy dozens of bottles in order to bathe in a fragrance, unaware that this can be deadly.) Japan, which experienced similar excesses in the 1980s, still accounts for around a quarter of global luxury-goods sales.

ECONOMIST: Why sales of luxury goods are slowing

Officers fear dozens of baby bottles covered with the same plastic stones could also be in circulation.

BBC: 'Bling' dummies seized from Kempton Park market

There were reports of violent outbreaks on the outskirts of the protest as it reached central Paris, with dozens of youths throwing bottles and lighting fires in a main shopping street.

BBC: Huge crowds join French strikes

On Monday night, police were attacked with bottles in Bond Street in the Waterside after they moved dozens of protestors who were blocking the Glendermott Road.

BBC: Loyalist protest in Londonderry