The apology forms a part of a confidential legal settlement between Oystercatchers and two WPP companies, strategic consultancy Everystone and branding agency The Brand Union.
In the apology, Oystercatchers admits supporting a number of individuals, including Crispin Jameson, the chief strategy officer of The Brand Union and chief executive of Everystone, and David Blyth, a principal consultant at Everystone, in their efforts to set up a venture known as The Great Game.
Blyth settled and apologised "unreservedly" in February, admitting to breach of contractual obligations and misuse of WPP's property and proprietary information, after The Brand Union and Everystone commenced proceedings in the High Court.
It is understood proceedings against Jameson are continuing.
"We make this statement to apologise unreservedly to Everystone Limited ('Everystone'), The Brand Union Worldwide Limited ('The Brand Union') and WPP for our entirely inappropriate involvement in the venture known as The Great Game, which was set up and promoted by Crispin Jameson, David Blyth and others whilst they worked at Everystone and The Brand Union. We deeply regret being involved in that venture in a manner that we know was wrong.
"Our conduct in supporting these individuals, when we knew they worked at Everystone and The Brand Union, by contracting with them to provide services, introducing them to prospects and jointly pitching for business, was totally unacceptable.
"We accept that we were complicit with those individuals in their flagrant breach of their duties to Everystone and The Brand Union, and we acknowledge that our actions amounted to a misuse of Everystone and TBU’s property and proprietary information. We were not entitled to profit from these wrongful actions and our settlement with Everystone and The Brand Union reflects the position.
"We acknowledge that as a result of our misconduct Everystone and The Brand Union have necessarily been put to unavoidable material cost in investigating, pursuing and seeking to remedy the position.
"Our conduct was plainly wrong as a matter of law. We accept that Everystone and The Brand Union were entirely justified in issuing legal proceedings against us. We have now reached a confidential settlement with Everystone and The Brand Union. We now look forward to putting this matter behind us."
Oystercatchers was unavailable for comment and WPP declined to comment.