Claydon, who is likely to work out his six-month notice period, is understood to be planning a three-month break. Sources say his longer-term plans include making investments in companies involved in growth areas that include mobile and digital.
His departure follows that of Martin Brooks, the Zulu chief executive, who is leaving to start his own agency (Campaign, 18 May). It leaves Zulu without a senior management team, but replacements are expected to be unveiled soon.
Claydon founded Zulu in October 2005, when he brought Claydon Heeley and Agency Republic into one group with the sales promotion agency Alcone and Code, a technology outfit.
He launched Claydon Heeley with Mark Heeley in 1991 and sold the business to Omnicom seven years later.
Claydon declined to comment on his departure.