John Wood, managing director of contract caterer Yes Dining, has left the company after six years.
In a statement Wood said he had gone "to pursue other interests".
He launched the business with Frank Bell, chairman of parent company Castle View, in 1999.
But an industry insider suggested Wood's departure might be linked to a dispute. "Wood had become disillusioned at Yes Dining because its profits were diverted for use elsewhere in the Castle View group," the source said.
They added that Wood had consequently lost his motivation to grow the business, saying: "It has been in the doldrums for a few years".
Bell rejected the speculation as "completely untrue".
"There is no question of that at all," he said. "John has simply realised that he wants to pursue his interest in sailing.
"Things are beginning to grow extremely well. I wouldn't have bought John's shares from him if they weren't."
Yes Dining has 20 contracts including the Greater London Authority and Allied Irish Bank. In 2004 it made a pre-tax loss of £5,725 on turnover of £5.1m.