The younger Stokes, who replaced former Woodside Petroleum boss Don Voelte as the CEO of Seven in April 2015, will now spend more of his time poring over Beach's accounts and operational plans while wondering how to make his oil and gas investments profitable.

Since Seven started buying into the Cooper Basin Beach shares have gone from more than $1 per share to half that, the company has burned through three managing directors (one acting) and it has severely curtained investment in response to the low oil prices.

Although it has also added the assets of Drillsearch Energy in that time, another company the Stokes empire had in its grip and one of Beach's most significant joint venture partners.

As Seven is a potential rival with Beach, the mid-cap Australian oiler said the usual protocols and other arrangements appropriate to the appointment of a director representing a large shareholder have been agreed with Seven and Stokes to protect any of Beach's confidential information, and address any potential conflicts of interest that may arise.

That issue has been in sharp contrast lately, with Voelte unsuccessfully suing the ABC for, he claimed, implying he used his directorships and knowledge while at Seven to "steal" Nexus Energy away from shareholders - a case Voelte lost yesterday.

If Seven's interest in Beach falls below 12.5%, the Adelaide-based oiler has the right to ask Stokes to resign.

"We are very pleased to have reached a sensible and commercial arrangement with our major shareholder and to welcome Mr Stokes to the Beach board," Beach chairman Glenn Davis said.

"(Seven) has made a very significant investment in Beach and is supportive of our strategy. Stokes brings to the board significant industry knowledge related to that strategy, together with his broad ranging business and commercial skills. We welcome him to the board and look forward to his contribution to Beach's growth."

Ryan Stokes said he said had confidence in the company and the opportunities for its future development, particularly following the merger with Drillsearch.

Making way for Stokes is Beach's longest-serving director, John Butler.

Butler joined Beach in 1999 after having been an alternate director to former managing director Reg Nelson between 1994 and 1998, during the rebuilding phase of one of Beach's darkest hours.

Beach's board and management have undergone sweeping changes in recent months, dating back to before the Drillsearch merger.