The private equity backer of one of Britain’s biggest corporate restructuring firms has become the leading contender to buy Kantar Media, the company which measures Britain’s TV ratings.

Sky News has learnt that HIG Europe has submitted a formal offer for Kantar Media, which is reported to be valued by its parent company’s shareholders at about £1bn.

HIG’s offer was said by banking sources on Monday to be “serious and credible”, although people close to Kantar Group cautioned that there was no certainty that a deal would be struck.

Kantar Media – which has a long-term contract in the UK with Barb Audiences – measures ratings data in scores of countries around the world.

It is a subsidiary of Kantar Group, which is majority-owned by the buyout firm Bain Capital.

A large minority stake is held by WPP Group, the FTSE-100 marketing services provider which on Monday saw two of its principal rivals – Omnicom Group and Interpublic Group – agree to combine in a landmark industry merger.

HIG’s interest in Kantar Media would represent a major deal for the private equity firm, which owns stakes in companies such as Interpath Advisory.

Last week, France’s Ipsos said it was evaluating an offer for Kantar Media, but subsequently withdrew from the process.

Buyout firms Cinven and Triton Partners are not thought to have made formal offers, although interest from other parties could yet emerge.

Bain and HIG have been contacted for comment.