Fox claimed that the programme's star Kevin Whately and himself had agreed to call it a day to prevent the series becoming "a bit samey".
"Kev and I have decided we want to do other things, otherwise it all gets a bit samey," he told The Daily Telegraph.
"I mean we could have gone on forever, but... Oh God, was I supposed to say that? I have no idea if I'm allowed to tell you it's ending. Bloody hell, what if I wasn't?"
ITV gave the show a seventh run in May, claiming that they "remain committed" to the Inspector Morse spin-off. The show has been a regular hit in the ratings for the broadcaster on both Sunday and Wednesday nights.
ITV1's Inspector Morse prequel Endeavour, which stars Shaun Evans in the lead role, was granted a full series commission earlier this year.