TV operator Sky said on Friday that Aberdeen Asset Management chief executive Martin Gilbert has been appointed its deputy chairman — and that James Murdoch, son of media mogul Rupert, will succeed Nicholas Ferguson as chairman.

The return of James Murdoch as chairman, four years after resigning from that job during a phone-hacking scandal, could increase speculation that 21st Century Fox might try to acquire the 61% of Sky that it does not already own.

James Murdoch is chief executive of 21st Century Fox. Rupert Murdoch, 84, is executive chairman of 21st Century Fox and News Corp.

One Sky shareholder, Royal London Asset Management (RLAM), described the appointment of James Murdoch as chairman as inappropriate, according to Reuters.

“Should Fox make a bid for Sky, investors need a strong independent chairman to protect the interests of minority shareholders and negotiate the best possible deal,” said Ashley Hamilton Claxton, corporate governance manager at RLAM.

Meanwhile, Sky said it gained 337,000 new customers in the quarter to December 31 and had its highest UK and Ireland customer growth for ten years.

The company said it had revenue growth of 5% to £5.7 billion in the six months to December 31, had its highest ever first-half operating profit — up 12% to £747 million — and it increased it interim dividend to 12.6p per share.

“We have extended our lead in content with a ground-breaking new long-term deal with Showtime, which complements both Sky’s original productions and our partnership with HBO to make Sky Atlantic the best destination for world-class drama across Europe,” said Jeremy Darroch, Sky chief executive.

“This will bring customers the return of great shows that include Fortitude, Game of Thrones and The Affair alongside new productions such as Vinyl, Billions and The Young Pope.”

James Murdoch has been a director of Sky since February 2003 and previously served as chief executive from 2003 to 2007 and as chairman from 2007 to 2012.

Sky said Nicholas Ferguson decided to step down as chairman and director of the company at the end of April after 12 years on the board.

“I am very pleased that James has agreed to succeed Nick,” said Gilbert.

“Having seen first-hand James’s contribution to and passion for Sky, the board feels he is uniquely qualified to become chairman.”

Gilbert has served on the Sky board since November 2011. He is chair of its audit committee and a member of its corporate governance & nominations committee.

From November 2014 to January 2016, he was the senior independent director.