Hassan Ceesay, 48 and of Greenwich, London, was jailed for ten years on Friday after pleading guilty to possession of the drug with intent to supply.

He was undone by an inquisitive and quick-thinking woman driver. Her remarkable afternoon at 2.20pm on May 1 when she pulled over on the 'straight mile' near Rugby because she had something in her eye.

There she saw two men apparently collecting brown boxes and loading them into a Peugeot car.

Prosecuter Vicki Lofrese told how the suspicious woman watched as the car pulled into a property owned by her friends to ask for directions.

When it stopped a second time, she and her friends noted the numberplate and then went to investigate the roadside.

There they found three cardboard boxes containing packages wrapped in brown tape.

Inside was the bulk of a 47.68-kilo haul of cocaine worth £2.4 million - or up to £4.7 million when cut with other substances.

Ceesay was stopped at Watford Gap as he returned to London. After claiming he had been kidnapped and forced to drive, he helped officers locate another box which he and the other man, no longer with him, had dumped.

The married father-of-five admitted he was acting as a courier, but initially claimed he had acted under duress.

Defending, Nick Devine said his client runs a taxi business and was contacted by a regular customer who asked him to pick up the packages, for which he was to be paid £400.

He said: "He was not particularly suspicious, but as soon as he arrived to collect them he became aware of what he was dealing with. Stupidly he loaded them into his car.

"They became aware they were under observation and Mr Ceesay decided he was going to have no more to do with it, dumping almost £3m of cocaine in the bushes."

Jailing Ceesay, Judge Faber praised the woman and her friends, whose "awareness and astuteness enabled the police to recover drugs which would otherwise have found their way onto the street".

He told Ceesay: "You have pleaded guilty to your involvement in what is on any view an extremely serious offence, the possession of a massive quantity of cocaine with intent to pass it on.

"You willingly allowed yourself to be involved."