It is also thought that the agency has picked up the lion's share of BBC briefs since the corporation split its advertising duties between the agency and Fallon in October last year.
However, neither of the agencies could confirm this at the time of going to press.
This will be the first time the BBC has used an outside agency to create a branding campaign for EastEnders, which has come under mounting pressure in recent times.
Not only has the actress June Brown joined public criticism of the storylines for being too depressing, but the show has seen its viewing figures gradually fall since its heyday in the mid-80s.
In 1986, the soap set a viewing record when more than 30 million viewers tuned in to see Dirty Den hand his wife Angie her divorce papers.
This is in stark contrast to the 6.1 million viewers - its lowest-ever ratings - who tuned in in September 2005.
On the same day, Emmer-dale, which generally plays third-fiddle to EastEnders and its main rival Coronation Street, was watched by 8.1 million viewers.
Meanwhile, Abbott Mead Vickers BBDO has created 14 new idents for BBC2 in a bid to refresh its on-screen identity.
Airing from 18 February, "2" has now become a window through which the world can be seen differently, while reflecting the range and diversity of content on the channel.