Just 24 hours after drafting in lawyers to threaten withholding £20m of severance payments the global advertising powerhouse said Sorrell's MediaMonks bid was based on information gathered while the exec was still at the helm of WPP – in breach of confidentiality clauses.
The legal row is designed to undermine the bid, with WPP claiming that Sorrell was "heavily engaged" in its own takeover efforts prior to his abrupt resignation in April amid allegations of personal misconduct.
Sorrell has hit back however, instructing his own lawyers to dispute the claims while demanding evidence to back up its assertions.
Unperturbed by the unfolding drama Sorrell reportedly flew to Amsterdam on Thursday (5 July) for further talks amid speculation that his S4 Capital investment fund remains the frontrunner to secure the €300m prize, with an announcement predicted as soon as Monday.
Sorrell is bound by confidentiality clauses in his employment contract which bar him from utilizing information gleaned while at WPP to pursue takeover targets of his own, potentially opening the door to a lengthy legal dispute.
MediaMonks is being targeted as the first plank in Sorrell's ambition to build a new "multinational communication services business".