The marketing communications group alleges that Wright, in his role as Porta CEO, “attempted to effect an unlawful conspiracy, as part of a project to allow Porta to back the acquisition of all or part of the Media Square Group,” according to a stock exchange filing.

Wright joined Porta – formerly known as TSE Group – in November 2010 with plans to make acquisitions that would reposition the sports consultancy as an integrated marketing and communications group.

Years before, he founded the PR agency Citigate and sold it to the Incepta group, which Wright went on to lead as CEO and chairman until 2004. Incepta merged with the rival PR group Huntsworth in March 2005, after which certain agencies – including Illuminas – were sold off to Media Square in a £63m deal.

In November 2009 Wright was put forward as a candidate to become a director of Media Square as part of an attempt by minority shareholders to remove the company’s chairman Roger Parry (pictured). The attempt ended in March 2010.

Media Square said it informed Porta of its intention to bring legal action on 11 October. It expects that the claim will be defended, although Porta itself has yet to comment publicly.

Editor’s note: Story updated to clarify that Parry remains chairman of Media Square.