Gray was amazed and saddened by the Hansie Cronje revelations

However, he regrets the fact cricket's anti-corruption unit did not get "more scalps" during his presidency.

Gray has been replaced as head of the ICC by Pakistan's Ehsan Mani after three years in office.

The Australian continually challenged the corruption issue head-on, having taken office days before former South African captain Hansie Cronje's match-fixing hearing.

"Obviously we were all shocked by the corruption issue, and none of us realised the extent of the problems cricket had at that time," Gray told Test Match Special.

"The threat is always there and the ICC will have to remain vigilant and ensure that the players don't get tainted again

"I believe match-fixing is out of the game, but I regret that we didn't get more scalps.

"We did not have legislative power to arrest people, burst into their house in the middle of the night to get evidence or cross-examine them under oath in a court of law.

"All we could do was act by finding out information and, by using persuasion, work in conjuction with local policing authorities.

"Knowing something and suspecting something is a long way from a conviction."

He ruined his life and almost the life of cricket Gray on Hansie Cronje

Gray had special words of praise for Lord Condon, describing his biggest achievement as ensuring the Englishman and his "excellent" anti-corruption unit remained independent.

"I was always constantly amazed whenever Lord Condon briefed us," Gray revealed.

"I did need to get Condon in place with authority and resources and I was determined that he wouldn't be subject to interference from anybody.

"There was some resistance to that because they didn't want some man running around bringing discredit to them.

"We won that one and making sure they were independent was the greatest thing."

Distrust

But it did not come easily.

"There is always a distrust of the English within cricket administration.

"Sometimes you'll see reports of a racial distrust, but I think it's more some of the colonies wanting to get back at the English for historical reasons.

"Paul Condon is and was establishment. He came out of Scotland Yard and there was a feeling of apprehension.

"But we got him, the anti-corruption unit scoped the problem and then tackled it."

However, Gray did reveal that gambling was still a major part of the game.

More than US$1m changed hands ahead of the India-Pakistan World Cup match - an estimated 80% of it illegally.