Last year, the committee invited a renewable energy expert from the NSW Office of Environment and Heritage to attend the meetings and provide advice. But Mr Newman is said to have been furious, claiming the adviser was "too pro-wind". Rather than discuss it with the committee, he contacted Mr O'Farrell, who promptly barred such staff from attending.

Changed the rules after lobbying: Barry O'Farrell.

When Mr Newman told the committee what he had done, some members were shocked, and pointed out that the guidelines permitted the state government to send representatives. "Well, I think that's probably being revised," Mr Newman said.

Such actions represented "a clear pattern of behaviour", Simon Chapman, a professor of public health at Sydney University, said. "They are trying to target any person who has expertise who may be able to provide advice at a senior level. Anyone who can refute the hearsay evidence of the anti-wind people is simply swept away."

In one of his letters to Mr O'Farrell, Mr Newman discusses the attendance of the renewable energy specialist as "Orwellian", adding "I am grateful for your intervention".