Anthony Gahan, co-founder of corporate finance adviser Wyvern Partners, told the Sunday Telegraph that his firm approached Aegis in May with a potential offer from private equity firm Doughty Hanson for the research business – but was rebuffed.

Doughty Hanson first started looking at Synovate 18 months ago, said Gahan, and is believed to have valued Synovate at around £600m, more than the £520m that the proposed deal with Ipsos is said to be worth.

Gahan said his firm first contacted Aegis by email saying it had a potential bidder that valued the business “substantially above £500m”, but received no reply. After Aegis revealed it was in talks with Ipsos, Wyvern made a formal approach to directors including chairman John Napier (pictured) and CEO Jerry Buhlmann, but was told that Aegis would not agree to meet with Wyvern unless it first revealed the identity of its client.

He told City AM that Wyvern first made contact with Aegis before Ipsos was “anywhere near the situation”.

“There has been no real desire to engage with us,” Gahan told The Sunday Telegraph. “We do not believe that there has been an exercise to test the market value of Synovate.”

Ipsos and Aegis revealed last month that they were in talks regarding a possible sale of Aegis’ research business, and have since said that those talks are exclusive. Private equity group Cinven has reportedly also expressed interest in Synovate, while WPP, GfK and Publicis have all ruled themselves out as rival bidders.

Gahan said shareholders in Aegis would be “looking for the highest value” from a sale of Synovate.

Aegis declined to comment today.