Gress joined Mortgage Next in 2003.
Mortgage Next acquired Mortgage Intelligence recently and moved its main office from Caterham in Surrey to Bournemouth.
Gress said she decided to leave her post at Mortgage Next because she did not want to relocate to Bournemouth.
"It was a difficult decision but Bournemouth would be such a long commute," said Gress.
Gress does not yet have a full time job but said she had spoken to the managing director of Mortgage Intelligence about the possibility of working on some events for the company in future.
"I am keeping my options open and if something comes along in events that's full-time corporate side, I would certainly consider it," she said.
Mortgage Next marketing supervisor Lara Daniell said that Sharon Mawby had been appointed head of sales and marketing following Gress' departure.
Carol Gress' biography:
* 1980 Marketing assistant, Argos Business Publications
* 1991 Head of incentives, events and travel, Guardian Royal Exchange
• Account director, Outsource Group
• Marketing services manager, Fuel
* 2003 Head of marketing, Mortagage Next