David Farrar just doesn't get it.

With regard to the mixed ownership model David Farrar writes,

This is the model that the unions and their allies have tried to destroy.

Everyone is a winner – the Bay of Plenty Regional Council and its ratepayers, Port of Tauranga’s minority shareholders and the company itself.

It is totally inappropriate to look at partial privatisation as a zero sum game, a game where there must be a loser for every winner. Partial privatisation can lead to a substantial increase in value and income for a regional council, or the government, if the listed company is well governed and managed.

Absolutely. There can be no argument that privately owned and managed companies do better overall than wholly owned public ones. By this I do not mean no private companies fail and no public companies succeed. Of course not. But if you look at decades of economic data across OECD countries, the difference is stark.

Yes and if you look at the economics literature you will also find that fully private companies outperform mixed ownership firms. Some insight on this is offered by a recent paper in the Scottish Journal of Political Economy (Volume 59, Issue 1, pages 1–27, February 2012). The paper "What Drives the Operating Performance of Privatised Firms?" by Laura Cabeza García and Silvia Gómez Ansón argues that the greater the amount of privatisation the better the performance of the firm. Not an entirely surprising result as the full force of market discipline can only be applied if the firm is fully in private hands but it is something for the government to keep in mind. It would suggest that any performance improvements due to the government's partial privatisation plans will be modest.

The abstract reads,

Using a panel data analysis of Spanish privatised firms, we study how different factors influence the operating performance of divested companies. The results show that it is not privatisation per se but other factors that matter. After controlling for possible sample selection bias related to government timing of divestments, we find that the greater the relinquishment of State control and the smaller the percentage of ownership held by managers and/or employees, the better the firms’ post-privatisation performance. Moreover, privatisations that are accompanied by liberalisation programmes and occur during buoyant economic cycles turn out to be more successful. (Emphasis added.)

When you look at the performance of mixed ownership firms they don't do as well as fully privately owned firms. For example, Aidan Vinning and Anthony Boardman in "Ownership and Performance in Competitive Environments: A Comparison of the Performance of Private, Mixed, and State-Owned Enterprises", Journal of Law and Economics vol. XXXII (April 1989) conclude

'The results provide evidence that after controlling for a wide variety of factors, large industrial MEs [mixed enterprises] and SOEs perform substantially worse than similar PCs [private corporations].'

So fully private firms out-perform mixed ownership firms. Thus if Farrar followed his own logic he would be arguing for 100% privatisation of SOEs.