Dowgierd, a former Fallon account director, who provided the business plan for Happen's launch, is understood to be looking at opportunities within digital marketing.
Brad Fairhead, Dowgierd's partner at Happen, who also runs the digital division, Hyper Happen, will remain in charge of both businesses. He is now seeking a replacement for Dowgierd.
Both agencies were set up a year ago to develop ideas beyond traditional advertising. They are joint ventures with Naked Communications.
In November, Fallon and Happen won the Tate group's £1 million creative and communications planning briefs. Happen has also picked up project work from Fallon clients such as Skoda.
The Happen businesses employ six full-time staff and draw on Naked's and Fallon's planning resources.
- Comment, page 44.