In a short statement, Cowie said Neil Pykett "had been relieved of his executive duties ... with immediate effect". Cowie insisted his abrupt departure had nothing to do with the group's financial performance.
Mr Pykett, who was on a three-year rolling contract and an annual salary of pounds 160,000, indicated in October that he wanted to leave Cowie in 1999.
But sources close to Cowie said Mr Pykett had become "de-motivated" after announcing his decision, leaving directors with no choice but to dismiss him without further delay.
It remains unclear if Mr Pykett, having signalled his intention to quit Cowie, is entitled to a pay-off. Cowie insists he will not receive a penny.
Mr Pykett was unavailable for comment. He joined Cowie 13 years ago and was appointed to the board in 1987. Recently he exercised options in Cowie to buy a large working farm in the Cotswolds.