“A substantial shareholder could push for board seats to gain...

“A substantial shareholder could push for board seats to gain information about the company to help a potential takeover bid or use board representation to try to control the company.”
It may be the case that recent new appointment was at the request of a, or several substantial shareholders.

Role of NED Non executive shareholderNon-executive director means a person who is not an executive director and not interested in the company's day-to-day operations. He or she is usually involved in planning and policymaking. The non-executive directors are expected to oversee the performance of the executive directors and the management.