As executive chair, Alps will work three days a week instead of her current four, but she will continue to play a key role overseeing the strategy, research and communications output of the organisation.
Alongside Alps, Thinkbox's executive team includes managing director Lindsey Clay, research and planning director Neil Mortensen, and marketing director Andrew MacGillivray.
Alps was appointed as Thinkbox's first chief executive in April 2006 and she was responsible for building up the organisation into a fully resourced operation, ending its relationship with strategic marketing agency Ingram.
The Thinkbox board has not had a permanent chair since Andy Barnes, former sales director at Channel 4, resigned at the end of March last year.
Julia Jordan, executive director, business and operations at UKTV will chair the Thinkbox board of shareholder directors for a year, before it passes to one of the other directors.
The other directors of Thinkbox are Jonathan Allan, Barnes' replacement as sales director at Channel 4; Simon Cox, vice-president, Turner Media Innovations; Jeremy Tester, director of brand strategy and communication, Sky Media, and Kelly Williams, group commercial sales director, ITV.
Alps said: "I'm looking forward to spending more time with my TV. My planner is so full that going to three days a week is the only option. Once that's cleared, I will have the opportunity to do a couple of other things.
"I shall never stop championing TV advertising's effectiveness and pressing for it to get the recognition and investment it deserves, or being fascinated by its expansion through new technologies.
"The Thinkbox team is well established, full of talent, and flourishing under the terrific leadership of Lindsey Clay and the directors, and with the support of a brilliant board, now chaired by Julia. It is the perfect time for me to take a step back."
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