Steeds joined the Incepta board in March 1997, and had executive responsibility for UK public relations, including Citigate, design and branding.
David Wright, executive chairman of Incepta, said that at Citigate, Steeds acted as an operating officer, liaising between the agency and the parent company.
Wright will act as his replacement.
Steeds was one of the founding members of Citigate when it launched January 1988, and was group finance director when it floated in 1997, but he has never held a client-facing role.
Wright said that Steeds had "decided to go on his own. It's a parting of the ways." It is not thought he will take another role in the PR industry.
Incepta's share price was up this morning rising 4.6% to 45.5p from its opening price of 41.5p.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the