Peter Clague was once the executive principal of private North Shore school Kristin.

A former top principal has been awarded $145,811 in court costs after his ex-wife allegedly tried to ruin his reputation.

Former Kristin School head Peter Clague was last year hauled to the Auckland District Court to answer a charge of assault - to which Judge David McNaughton quickly put an end.

Clague's ex-wife Jehanne Denham alleged that two months after the pair married in 2010 he pushed her to the ground, allegedly causing significant bruising to her tail bone.

She said he shook her with force, telling her to "shut the f... up".

READ MORE:

* Judge drops principal's assault charges

* Private prosecution assault trial for top principal Peter Clague

However, she didn't lay a formal complaint until 2014, and then took a private prosecution against Clague through Queens Counsel Marie Dyhrberg.

However, in July last year Judge McNaughton threw the charge out, saying a jury would have been unable to convict and that the case had been brought in bad faith.

"He's suffered enough. I'm bringing this to an end now," he said at the time.

Clague has since sought costs for the court exercise, with his lawyer arguing that aside from bringing the prosecution in bad faith, Denham had also failed to respond to court directives or provide disclosure.

She had also allegedly launched a "sustained vicious and untrue media campaign on the part of Carrick Graham and [WhaleOil blogger] Cameron Slater".

Defence lawyer Mike Lloyd alleged that there had been articles in the United Kingdom press about the prosecution not long after Clague arrived there to take up a post at Bromsgrove School.

"Mr Lloyd emphasised the collateral damage to the Kristin school community and submitted there was a very strong need for deterrents of bad faith prosecutions of this sort," Judge McNaughton's judgment said.

Marie Dyhrberg QC opposed full costs being awarded, saying it was "manifestly excessive", that there was "strong evidence" to support the prosecution and a lack of evidence to support the other allegations against Denham.

However Judge McNaughton ruled Clague should receive the full amount of $145,811.37.

"Whether there was any evidence to support the informant's allegations, in the end I have decided [that] carries very little weight," he said.

"The informant's claims were grossly and maliciously exaggerated in order to destroy the defendant's reputation, to inflict damage on the Kristin School and to obtain the advantage in the informant's relationship property claim.

"It is difficult to imagine a worse case of bad faith. I agree with Mr Lloyd that the various media campaigns including the UK campaign are an extraordinary aggravating feature of the case which take it well beyond the conduct described in any of the other reported cases involving the award of full indemnity costs on the basis of bad faith."