Spring in Finland’s capital and it’s still minus four degrees at midday. Staying warm requires so many layers of clothing that the pickpockets have taken to asking for your wallet rather than lifting it. They pose as members of the city’s police.

Coloured leaflets placed by the plastic menu-holders on each table in a local restaurant carry a warning from the Helsinki police department. They read: "Beware of people impersonating policemen. True Finnish policemen never ask to see your wallet. Never obey a request to show your wallet."