Mark Riches, co-founder and non-executive director of FIRST has left the agency after almost 23 years.
Riches leaves the agency in good shape, with FIRST having reported 48% profit growth in October 2018 for its latest financial year.
"It has been an amazing journey, and this has only been possible with the support of our clients," said Riches.
"It feels like a good time to step aside, as I leave an extremely strong business with a clear focus on the needs of our clients. FIRST’s people and leadership in our teams around the world are best in class."
At the same time as the Clive acquisition, Riches moved to a non-executive director role in a reshuffle of FIRST’s leadership team.
Riches added: "I'm going to take a break and focus on some of my other advisory roles for businesses in the sector, such as Fay Sharpe's brilliant Fast Forward 15 mentoring scheme.
"Other than that, I will be moving house and taking a year out."
A statement from FIRST said: "Mark will continue to support our growth and success from the side-lines, as we approach our 25th anniversary."
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