The move is part of an initiative by JWT's worldwide chief executive, Bob Jeffrey, to bolster the agency's image. Jeffrey took up the network's top job at the end of last year.
The slogan was introduced in the 60s, at a time when JWT was struggling to stand out against a range of up-and-coming creative hotshops. It was used in an attempt to persuade clients to look at JWT in a new light, while calling attention to the creative work the agency was producing.
Now, once again, clients will be sent out reels tagged with "J. Walter Thompson did that" as the network looks to redefine its public face. It is not yet known if the initiative will be incorporated across all of the network's offices.
The slogan will not be used as part of the JWT official brand positioning, which is also under consideration by Jeffrey.
Separately, the London office is continuing its hunt for a managing director following Ros King's appointment to the role of global business director on Kraft.
The agency is recruiting externally to replace King, who leaves at the end of May.