How are people-smuggling gangs exploiting English Channel crossings?

A group of people thought to be migrants adrift in a dinghy before being rescued off the coast of Folkestone, Kent (Gareth Fuller/PA)

The sinking of a migrant boat with the loss of 31 lives off the coast of France has once again raised concerns about the people-smuggling trade.

For years law enforcement on both sides of the English Channel have been playing a game of cat and mouse with criminal gangs as tactics change and evolve.