The operation to land £1 billion of cocaine was going like clockwork: the catamaran had glided into position in the sea off west Cork and the cargo was being ferried ashore to a remote location, ready for distribution across Britain.

Months of planning suddenly went awry, however, because of the simplest of blunders — somebody put diesel in a petrol engine. The mistake caused an inflatable boat to capsize, tipping dozens of bales of cocaine into the choppy waters and casting one of the drug dealers into the sea.

When the emergency services were alerted, police found 61 suspicious packages floating around the upturned boat in Dunlough Bay, west Cork.

Yesterday four men were convicted for attempting to smuggle what became the largest seizure of cocaine in Britain and Ireland, on board the ironically named Lucky Day.

Joe Daly, 41, from southeast London, Martin Wanden, 45, of no fixed address, and Perry Wharrie, 48, from Essex, who were carrying out the orders for a criminal syndicate based in Britain and Spain, were jailed for their role in transporting and storing 1 tonne of high-grade cocaine.

Wanden and Wharrie were each sentenced to 30 years and Daly to 25. A fourth man, Gerard Hagan, 24, from Liverpool, who pleaded guilty, will be sentenced later.

Wharrie was jailed for life in 1989 for the murder of an off-duty police officer and released in 2005 on licence. Wanden was convicted in absentia by a French court in 2003 for drugs smuggling, and Daly also has previous convictions.

None of them, however, has admitted who poured the diesel into two high-powered petrol Yamaha outboard motors last July. Police believe that another six men who were involved in the operation escaped.

The ten-week trial at Cork Circuit Criminal Court featured characters with names from the pages of an airport novel, including “Big Al” and “the Gruesome Twosome”, while others had multiple identities supported by false passports.

The bungled operation infuriated a feared Colombian drugs gang who lost millions of pounds. The evidence gathered along the Irish coast led police to reconstruct a trail taking in Britain, Spain, South Africa, the US, Barbados and Colombia.

Officers also recovered equipment including mobile and satellite phones, GPS locators, three high-powered 4x4s, saloon cars, boats and a catamaran, as well as enough cash to fund a large group of people for up to six weeks in Ireland.

The cocaine recovered from the sea was 75 per cent pure. When sold on the street the drug is usually only between 12 and 15 per cent pure. By some estimates the haul could have raised more than £1 billion had it reached the streets.

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