What special bullets did the police use to foil that £80m robbery?

When the flying squad swooped on a gang planning to rob a warehouse near Heathrow on Monday, they used Hatton rounds to take out the tyres on their white van.

Instead of being made from lead, Hatton rounds are made from a molten mixture of wax and metal powder. The result is a slug that measures nearly 2cm in diameter, weighs 50g and can do jobs other bullets cannot. They are so big, they can only be used in Magnum shotguns.

"We designed them originally to blow doors off hinges," says Ross Clucas, of Clucas MOE, the Hull company that makes Hatton rounds ("MOE" stands for "method of entry"). The rounds work so well because they carry a decent punch, but also disintegrate on impact, so they don't go any further or ricochet dangerously. The safety aspect makes them a favourite of armed police in hostage situations.

Subsequent tests found they were also good for shooting out tyres. "They'll punch through the wall of a lorry tyre and because they've got a wax binder, when they hit the rubber, they tend to stick," says Clucas.

Safety is also why Hatton rounds are typically used for immobilising getaway vehicles. If police officers had used ordinary bullets or shotgun rounds, which spread shot over a wide area, they could have injured or killed the robbers or bystanders.

Though Hatton rounds are undoubtedly safer than regular bullets, you wouldn't want to be hit by one. "The trauma would be like being hit with a Magnum round," says Clucas. "If you got hit in the arm, the shock wave that would go through your body would probably be enough to kill you."

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