He will work along side Dominic Allkins, recruited by Portlock as the company's first data planning director when it launched last year.
Chauhan will be responsible for client development and management across Action Aid, pet charity PDSA, the Royal National Institute for the Blind and the National Children's Hospital.
He joins from Tequila where he worked for six years as a senior data planner within the company's customer insight team. He has also worked with blue-chip clients Vauxhall, News International, Chevrolet and Morgan Stanley on data and direct response planning.
Portlock said: "We are making it a priority to appoint best of breed consultants, such as Chet, who able to meet the challenging demands of a rapidly growing and varied client base."
Portlock left WWAV in 2000 and set up The John Watson Partnership, a management consultancy for agencies, with WWAV's former chairman John Watson and former planning director Tony Masters.
Direct marketing agency Watson Phillips Norman, formed by Watson, is a shareholder in Marketing Metrix, with the data consultancy working out of WPN's offices.
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