The common bond between the two companies - of bringing the Bard to the masses - has been broken.
The RSC is guilty of "a raiding exercise", neglecting educational and community activity, says Michael Bogdanov, head of the ESC.
That is "a gross calumny," retorts Adrian Noble, artistic director of the RSC, adding for good measure that Mr Bogdanov's comments are "irresponsible" and "destructive".
The falling out is remarkable one. Until recently, Mr Noble would invite Mr Bogdanov to stage plays at the Royal Shakespeare Company, and championed his work there.
But now Mr Bogdanov has turned on his former colleagues with a vengeance.
The focus of the confrontation is Newcastle upon Tyne. The RSC plays a month-long residency in the city, and has done so for 21 years.
The ESC - a company which tours plays nationally - has moved to Newcastle and is using it as the base for educational activity and for launching its tours.
It is perhaps significant that both companies might now be chasing money from the same funding sources for their Newcastle operations.
Mr Bogdanov claims in an article in the North-east arts journal The Northern Review that the RSC's residency is "just a raiding exercise on Newcastle, for five or six weeks of the year which takes the city's money".
He accuses the RSC of failing to set up educational and community activities, and says it has "devastated" Newcastle's theatre output.
"I'm not saying the RSC shouldn't come to Newcastle," he added. "But what is wrong is that the policy has not opened out and developed after its initial impact. The RSC should have had a much more comprehensive and ideological stance - which is what I hope we are now supplying."
Last night, Mr Noble responded: "I feel saddened that Michael Bodanov has found it necessary to attack the RSC, presumably to subvert funding for his own plans in this region ...
"The RSC's commitment to the North-east is indubitable. Each year, between 12 and 16 Stratford productions have formed a month-long Newcastle season before transferring to the Barbican Theatre in London. Over this time, the RSC has formed a great bond with the people of the North-east."
And, plunging the dagger back into his attacker and erstwhile colleague, Mr Noble warned that the ESC's educational activity could affect the work of the North-east's own companies.
He said: "I entirely support Michael for wanting to develop further community and educational activities in the region, but it would be wholly wrong if these activities were to eventually affect the work of the region's indig- enous theatre companies, like the excellent Northern Stage, who must have prime responsibility for this work."Reuse content