Forty years on, the rivalry between The Beatles and The Rolling Stones is still simmering. And now we have our own, albeit less rock-and-roll, equivalent in the media agency world.
There is a case to be argued that the two giants of media buying, Omnicom's OPera and WPP's Group M, are shaping up like The Beatles and The Stones.
While some perceive that Omnicom is claiming the creative "nancy boy" high ground, they argue that, based on recent spats with media owners, Group M is a more muscular, aggressive act.
Such generalisations aside, what is becoming apparent is that Omnicom and WPP are adopting totally different approaches. Group M has been established as something far beyond a trading entity: as a parent company for the three main networks - MediaCom, Mediaedge:cia and MindShare - plus its smaller media operations.
The UK bosses of each agency report to Stephen Allan, the Group M chief executive. This has its benefits - not least sharing between the companies on broader issues than trading and a strong central management team - yet WPP's critics argue that Group M casts too large a shadow over its constituent brands and that this could damage their performance and create resentment among staff and clients.
WPP's challenge over the years will be continually to refresh and re-establish the three agency brands, if it is to avoid resembling an amorphous mass. It will be interesting to see, for instance, what MediaCom comes up with to reassert its brand in the UK with the Group M umbrella hanging over it.
OPera only exists in a few markets, because of Omnicom's reliance on the OMD network while PHD is still being rolled out. It is described by management as a service for its companies, rather than a parent. Essentially, it involves itself in trading and not in management decisions at its constituent agencies, with OMD and PHD run as separate entities not reporting to the joint chairmen of OPera, Nick Manning and Tess Alps.
This has its upsides, but the danger is that OPera is not close enough to its agencies to work effectively.
Nobody yet knows which holding company has the right approach. The different methods seem to have evolved out of the style and structure of each holding company. In the end, one will emerge as the better model but, for the time being, there's room for both. But, as someone who thinks the Beach Boys are better than The Beatles or The Stones, I reckon there's also bound to be a third way.