The combination of higher rents, the credit crunch and a downturn in marketing spend are putting pressure on ad agencies.
A ripple effect of niche financial firms spreading out from their traditional bases in the Mayfair and St James areas of West London, is also pushing up rents.
The 'Moving Medialand?' report, commissioned by real estate specialists Jones Lang LaSalle, says the migration of financial businesses across Regent Street and Piccadilly to Soho and beyond has resulted in higher occupational costs in the West End than at any time over the past 15 years.
George Roberts, head of West End Agency at Jones Lang LaSalle, said: "Location change for advertising agencies could certainly be viewed as an opportunity to manage property costs and one that is widely cited within the property industry.
"The top agencies in London cluster around the core of Soho and Noho [the area north of Oxford Street]. They may well be driven by cost into other West End locations such as Paddington, Kings Cross, Victoria, Hammersmith and Southwark."
The report suggests that the top network holdings companies, such as WPP, Omnicom, IPG and Publicis, may consider consolidating office space under one roof.
Traditionally, groups resist this arrangement to avoid upsetting clients where there are potential conflicts between rival agencies.
Stephanie McMahon, associate director of UK Research and author of the report said: "Our view is that creativity will surpass pragmatism until the property cost threshold is breached, resulting in those who need to make a move to consider cutting costs through co-location, space reduction, lower quality stock or moving to other parts of the West End.