Traditionally referred to as the 'Costa del Crime', the Spanish costas became a popular haven for British criminals in the 1980s because of their complicated extradition laws. British dealers moved their operations to the sun and were eventually followed by their Irish counterparts.

The near 5,000 kilometres of coastline mean that it is relatively simple to smuggle in drugs that have originated from South America and then bring them through countries like Morocco and Algeria.

Spain is the European clearing house for organising large-scale drug importation and it is cheaper to buy drugs in bulk in Spain than anywhere else in the EU. They are broken up there and then smuggled across the continent through ports by barons who have established seemingly legitimate importing companies.

This means that millions of euro worth of cocaine, heroin and cannabis is often secreted in hidden compartments in trucks importing fresh fruit and vegetables and other legal goods though Rosslare and Dublin ports. A fruit importing company owned by Christy Kinahan's son Daniel was seized by a Spanish judge last Wednesday. Another of the main reasons for Spain's popularity is the reputation of the Spanish police for being particularly lax and turning a blind eye to organised crime. While this reputation was certainly well deserved in the 1980s and 1990s, international pressure has forced the Spanish to up their game and do more to prevent the drug barons from doing their business with virtual impunity.

Cooperation with international police forces has grown by nearly 50% since 2006 – as seen by last week's raids – and the introduction of European arrest warrants has meant that things have tightened up considerably, meaning that non-accession countries like Turkey and Latvia are now emerging as new bases for the barons.

The gardaí and the Spanish police share such vast amounts of intelligence that a detective sergeant is permanently based in Madrid to act as a liaison between the two forces.