The BBC's George Eykyn: The plot was related to Far Eastern gambling syndicates

But even after British police had arrested a number of conspirators in a scam to interfere with the floodlights at Charlton Athletic's ground, they were still unaware of the scale of the crime involved.

The plot to rig the lights at the Valley three days before the ground hosted Liverpool was planned in Malaysia and executed by gang members with the collusion of a corrupt Charlton security official.

Eight more games

If it had succeeded, it would have netted an estimated £30m for the criminals that operate Asia's illegal betting industry.

Malaysia: More than 100 players and officials arrested

British police officers - acting on a tip-off - were lying in wait when Wai Yuen Liu and two Malaysian co-saboteurs arrived at the Valley on the evening of 10 February.

Four men in total were arrested and a search of Liu's car and the Malaysian pair's hotel room revealed enough equipment to wreck the lights at another eight games.

In a period of 15 months, the betting syndicate had already interfered with two Premiership games without arousing the suspicion of British football authorities. The Valley was third on the list.

They were significantly helped by a corrupt insider - Charlton security supervisor Roger Firth - who was paid £20,000 for letting the saboteurs into the ground.

Lack of evidence

The police also discovered the names of another two key individuals in the Charlton conspirators' personal belongings.

Grobbelaar case: Unwanted publicity

One was employed at West Ham's Upton Park and the other at Wimbledon's home, Selhurst Park, when blackouts occurred at those grounds in 1997.

Both men were arrested, but escaped charges due to lack of evidence.

It was Firth, however, who initiated his own downfall after a clumsy attempt to bribe a fellow security guard with £5,000 to allow the sabotage to go ahead.

But the arresting officers from the Metropolitan Police Organised Crime Group only understood the full significance of the case when it was discovered that the tampering at the Valley would have lead to complete failure of the lights.

Awaiting sentence

When put beside the failures at West Ham and Wimbledon, the attempt to blow the floodlights formed part of a clear pattern.

Popular: Liverpool, Arsenal and Manchester United

Acting FA Executive Director David Davies then ordered immediate checks to be carried out at all Premiership grounds ahead of the weekend's fixtures.

Firth, 49, and the Malaysians, Eng Hwa Lim, 35, and Chee Kew Ong, 49, have admitted conspiracy to cause a public nuisance and are awaiting sentence.

Lui, 38, denied any involvement. He has been found guilty and is also being held pending sentencing.

English clubs like Manchester United, Arsenal and Liverpool have massive following in many Asian countries.

Premiership target

Blatant match-rigging - especially in Malaysia where more than 100 players and officials were arrested for corruption in the mid-1990s - has driven more and more disillusioned fans to pin their loyalties to English clubs.

It made the Premiership a logical next target for the betting syndicates that prey on the massive popularity of gambling in the Far East.

Unwelcome publicity accompanied the acquittal of Bruce Grobbelaar, Hans Segers and John Fashanu on match-fixing charges in 1997.

It is then that the police believe the gangs shifted their efforts to technical sabotage, specifically tampering with floodlights.

Complex scam

The betting system worked principally around encounters between the largest clubs and the smallest in the Premier League.

For example, in the Liverpool versus Charlton game, the south London side would be given a one or two-goal handicap.

If things went according to plan, the fans would still back Liverpool to win. Assuming that Charlton were still "ahead" on handicap by the start of the second half, the syndicate would then kill the lights.

Under betting rules, the result - and bets made on it - stood if the match was abandoned after half-time, allowing the gangs to rake in huge sums on "rigged" matches.