Shares in GPG plunged more than 7% yesterday after the announcement but retraced some losses to trade around 65c.
In his surprise personal view, lodged with the New Zealand stock exchange last Friday, Mr Gibbs called for the board-backed demerger plan to be abandoned.
He publicly approved the proposal when it was announced in mid-June, but subsequently said it did not have shareholder support and "would not succeed".
The demerger proposal was to spin off and float $NZ580 million of Australian assets.
Mr Gibbs, who is well known for his forthright views, advocated instead a year-end cash distribution to shareholders, restructuring of the GPG Group and preparation made for the sale or float of loss-making London-based threadmaker Coats, with the proceeds returned to shareholders.
GPG chairman Sir Ron Brierley said yesterday on the sacking of Mr Gibbs that the statement last week was a "serious breach of boardroom protocol" and "there was no alternative to the action taken".
"This action has been taken with much sadness but was unavoidable.
"Tony was a great achiever for GPG in earlier times and we worked together, closely and effectively, for nearly 20 years," he said yesterday.
Otago-Southland branch chairman of the Institute of Directors in New Zealand Stuart McLauchlan was "not surprised" by the sacking, saying Mr Gibbs had clearly "broken protocols" of any board by going public on issues which would normally be dealt with by the board chairman.
He noted GPG was unusual in having three directors based in New Zealand, Australia and the United Kingdom all "vying for [financial] resources" and Mr Gibbs' statement may have been made "out of frustration, for which he was now being held accountable".
Mr Gibbs could not be similarly sacked from his other public company positions as that process would have to be undertaken at an annual meeting, Mr McLauchlan said.
Forsyth Barr broker Suzanne Kinnaird, who picked the demerger proposal would find little shareholder favour or deliver value realisation, said yesterday Mr Gibbs' Friday denouncement saw GPG share prices spike, "indicating shareholders were in agreement with his views".
Mr Gibbs said yesterday he was dismissed "quite legally" during a telephone conference and maintained "I did what I did because I believe it was the right thing for everybody", NZPA reported.
"We have had a very strong difference of opinion," Mr Gibbs said.
Sir Ron said Mr Gibbs' statement on Friday was not seen, or authorised, by the GPG board before release and was contradictory to earlier external independent advice sought by GPG.
"The board is of the view that the strategy proposed by Mr Gibbs in his personal statement is inappropriate because it fails to take account of the complexities inherent in GPG's current structure," Sir Ron said.
He said GPG's current business model was not optimal and had substantial cost and complexity associated with it, including investments at varying stages of maturity and liquidity and tax consequences on different types of proposed shareholder distributions.
Sir Ron said "in light" of Mr Gibbs' sacking and "shareholder feedback", an independent subcommittee of the board would be established to review the proposal, consider variations and modifications, if any, and consult shareholders.
Mr Gibbs, who has about 10 million GPG shares which were valued about $6.5 million yesterday, will keep his role as chairman of insurer Tower and Turners and Growers, two of GPG's largest New Zealand investments, the New Zealand Herald reported yesterday.
