"I'm happy here at Rangers and I'm committed to my five-year contract but, in football, you just never know," he said.
"I have experienced it before when I was at Fulham and I signed a four-year deal then left the club six months later.
"So, you can never say for sure what's going to happen. I've always said I'd like another crack at it in England.
"I enjoyed it down there and it's probably the best league in the world. There's so much quality and so much money being invested."