Garry Edwards must have known something horrible was afoot when his evidence at a corruption inquiry was interrupted by a mystery witness.

As the Liberal member for Swansea resumed his seat in the public gallery, John Macgowan, a senior adviser in the Baird government, made his way to the witness box. And what he had to say was devastating.

Mr Edwards had just told the the Independent Commission Against Corruption that Newcastle property developer Jeff McCloy gave him an envelope in the time leading up to the 2011 state election.

He said he gave the envelope, without looking at its contents, to his campaign treasurer Max Newton, who had since died.