Christchurch businessman and rich-lister Mark Stewart has been biding his time with Wakefield Health.

He moved yesterday to take a controlling stake in the North Island private hospital operator four years after securing a near 20 per cent stake.

Stewart is partnering with the Royston Hospital Trust Board in a joint partial takeover bid for just over 50 per cent of the shares in Wakefield Health.

Yesterday he did not want to comment about the signalled partial takeover.

When the Stewart family raised its stake in Wakefield Health to nearly 20 per cent in mid 2008, Stewart said back then there was no takeover pending.

Four years later the family has made its move. Four months ago it exited its investment in old Canterbury firm Ebos, a supplier of a range of products including pharmaceuticals to the healthcare sector.

The foundation of the Stewart family wealth was built by the late Sir Robertson Stewart, who founded electrical goods company PDL, selling several decades later to the French electrical goods company Schneider.

In 2008 the Stewarts spent about $25 million on a 19.31 per cent stake in Wakefield.

The demographic of New Zealand was getting older and sicker and the public health system was under stress. There would be a lot more elective surgery going into private institutions, Stewart said then.

"There's lots of possibilities if you take a long-term view . . . It's trying to get into businesses that really have some growth potential in the long term," he said in 2008.

- © Fairfax NZ News