Taylor Nelson Sofres, the market researcher, has swiftly rejected an improved £995 million bid from Sir Martin Sorrell’s WPP.

The rejection of the revised offer took only a matter of hours and was helped by the fact that the offer worth 241.5p per share today compared poorly to the 246p that TNS shares closed at today. TNS continues to favour an all-share merger with GfK of Germany.

WPP said it was “disappointed that our latest attempt to engage with TNS on a friendly basis has met with such resistance”.

The previous bid, 11.5p lower than today’s and also in cash and shares, was made last week.

WPP stopped short of indicating it would be prepared to go hostile, although there was speculation that it could be forced to do so. WPP is unhappy that it is not being given access to TNS’s books as well as GfK.

Meanwhile, TNS could not put a timetable on when it would release more details of its plans to merge with GfK.

Initial details of the 50-50 merger were revealed at the end of last month, following press speculation, but the two parties are yet to update investors on the level of synergies they hope to expect after nearly a fortnight’s intensive work. WPP sources have questioned whether this indicates that the plans are not proceeding smoothly.

The combination of TNS and GfK would create the world’s biggest market research specialist. WPP has long signalled it is keen to expand in market research, which Sir Martin Sorrell regards a source of healthy growth in the future.

TNS Chairman Donald Brydon said the revised offer substantially undervalues the company even on a standalone basis.

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