GfK, the German market research group, has joined forces with a financial bidder in a last-minute attempt to prevent WPP from winning control of Taylor Nelson Sofres (TNS), The Times has learnt.

The German company, which is in talks with TNS about a nil-premium merger, plans to top any bid that WPP’s chief executive, Sir Martin Sorrell, may announce today.

If WPP tables a cash and shares proposal of 280p a share, the GfK consortium may consider a 280p pure cash offer, valuing the company at about £1.2 billion.

If WPP announces its withdrawal, GfK is under no pressure to bid with its unidentified partner and the original plan for a nil-premium merger with TNS will take effect, subject to shareholder approval.

The board of WPP was meeting last night to decide whether to make a formal bid for TNS before today’s “put up or shut up” deadline that was imposed by the Takeover Panel.

The advertising and marketing services giant is expected to announce its intentions as early as this morning.

A pure cash offer from WPP is highly unlikely. WPP has made it clear previously that if it made an offer for TNS, it would be structured to ensure that WPP’s credit rating would not be jeopardised. It is thought that the group believes a cash-only offer could have an impact on its credit rating.

GfK has been keen to find an alternative solution if TNS shareholders accept a further proposal from WPP. WPP’s last improved indicative bid of 260p a share, made up of 173p in cash and 0.1889 of a WPP share for each TNS share, valued TNS’s equity at £1.08 billion at WPP’s closing share price last Wednesday of 460½ refused to be named, said last week that it wanted to see WPP table an offer closer to 300p, although it may consider one at about 280p. There were mixed views about WPP’s last approach of 260p. Some analysts said that the WPP offer represented a fair price for shareholders and a premium of 52 per cent on TNS’s undisturbed share price of 171p.

Collins Stewart said in a note that the approach represented an “excellent deal for TNS shareholders”, whose share price has been propped up by the possibility of a WPP offer. Some hedge funds invested in TNS are thought to have shown support for WPP’s offer.

WPP wants to merge TNS with Kantar, its own market research unit, to become the second largest market research group after Nielsen. The combined group would have estimated combined revenues of $4 billion (£2 billion), doubling Kantar’s $1.9 billion figure for 2007. TNS declined to comment.

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