Vector completed the purchase on Tuesday and AGL-appointed directors Greg Martin, Mark Harper and Greg Hayes immediately resigned from the NGC board, to be replaced by Vector chairman Michael Stiassny, directors Greg Muir and Brian Plimmer, along with chief executive Mark Franklin.

They join NGC's existing three independent directors Richard Bentley (former NGC chief executive), Rick Bettle and former Labour Cabinet minister Fran Wilde.

Stiassny said the AGL purchase price was NZ$2.91 per share (being the original NZ$3.00 per share offer announced on October 10, less the special dividend of 9 cents per share paid by NGC on November 3).

“The acquisition of a majority stake in NGC is an important transaction for not only Vector, but for New Zealand," Stiassny said.

“Not only does the acquisition add significant scale and diversity to Vector's current infrastructure portfolio, it also ensures another valuable infrastructure asset is back under New Zealand ownership.

“NGC is a major player in the New Zealand energy sector and we look forward to working with its management to continue the growth and development of the company in the future."

Present NGC chief executive Phil James - an AGL appointee - is expected to leave NGC in the new year. But Stiassny has so far declined to comment on who might replace him.

Stiassny has also not commented on any other possible management changes within NGC, nor on any synergies that could be gained from merging the two network companies.

Vector's takeover offer to other NGC shareholders remains open until February 4.