John Napier is to replace Colin Sharman as chairman of the advertising and media group Aegis.

Napier has joined the board as a non-executive director and becomes non-executive chairman on July 17, when Sharman retires after more than eight years in the role.

He joins Aegis from the Royal & SunAlliance Group, where he has been chairman since 2003.

Napier was chief executive of AGB, the market research and information company, in the 1980s.

He was executive chairman and then chairman of the water utility Kelda from 1999 to 2008, chairman of the grocery wholesaler Booker from 1998 until 2000 and chief executive of the recruitment specialist Hays from 1990 to 1998.

"After a thorough search, we are delighted to have recruited John. In him, we have found someone with considerable board experience at the highest levels," Sharman said.

"He is a proven chairman who has delivered to shareholders, and brings international business skills and familiarity with marketing services," he added.

"Having been chairman [of Aegis] for eight and a half years, it is time for me to step down. I have immense pride in what Aegis has achieved – growing almost four-fold in that time."

The diversified media company, which owns the Carat media buying network and the Synovate market research group, had been fending off attempts by the French financier Vincent Bolloré, who holds a 29.9% stake in Aegis, to gain board representation. Bolloré said this month that he was "not in a hurry" to resume attempts to win seats on the board.

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