Rumours had circulated that Walters' arrival would signal the end for Forrester, but City chairman Adam Pearson says there's no truth in them.
He said: "Jamie isn't going anywhere. He's our player and that's how we want it to stay. He's still an important part of Peter's plans.
"As for Grimsby, some people have looked at the situation and jumped to entirely the wrong conclusion. It's absolute nonsense."