LONDON: it was never for one  moment likely that WPP Group ceo Sir Martin Sorrell would sit idly by as his quarry – global market research firm  Taylor Nelson Sofres – sealed a merger deal with Germany's GfK.

For those who follow Sir Martin's behavioural patterns it was not a matter of whether he would strike – but when.

On Monday Sorrell invoked the UK's takeover code, forcing TNS to backtrack on its refusal to open its accounts. In a statement released same day TNS revealed: "TNS has now received a notice from WPP Group pursuant to Rule 20.2 of the Takeover Code requesting information in relation to TNS."

As required under the nation's takeover rules, TNS undertook to provide WPP with the same information it has already made available to GfK

Sorrell, who views TNS as a juicy morsel for WPP's own research business Kantar, told Bloomberg News over the weekend that he was considering either raising his unsolicited (and rejected) offer or making a hostile bid for TNS.

TNS is not enthused by Sir Martin's interest – hostile or otherwise. It's statement made this crystal clear: "The board of TNS remains committed to implementing the merger [with GfK], which it believes to be in shareholders' best interests."

Data sourced from Financial Times; additional content by WARC staff