Lucky break Sea chase that netted Border Force an £18m catch of the day

To the surfers and dog walkers on the Cornish beach it must have looked like a scene from a thriller. An ocean chase ending with two boats crunching aground on the sand, a stumbling attempt by three men to escape into the dunes, dramatic arrests and the discovery of millions of pounds' worth of cocaine.

- Steven Morris

For the investigators it was the start of a painstaking investigation that has shone a light on a tactic used by South American drug gangs and British organised crime groups known as at-sea drop-offs or Asdos.

What made Operation Libellary particularly satisfying for the investigators is that they caught people involved in a number of different aspects of the crime - including a fisher fallen on hard times, a Colombian enforcer, and members of an "Essex crime group" believed to be the buyers who would have sold the drugs on the streets of south-east England.

The senior investigating officer, Barry Vinall of the National Crime Agency (NCA), said the seven men caught and convicted of conspiracy to import class A drugs were pivotal figures in the crime. "You've got organisers, logistics, security, customers," he said.

It began with a lucky break for the law enforcement agencies. The UK Border Force cutter HMC Valiant was patrolling off the coast of Cornwall on 13 September last year when officers noticed a rigid-hulled inflatable boat (RHIB) on the horizon. They knew there was a "mother ship" in the area so went to take a look and the RHIB sped off.