My children are 5 and 7. We've always had a wood burner so they know it's hot and that they must be careful.
What age have people felt it's safe to stop using the fireguard? Ours is set into the wall, so no risk of them hurting themselves on the slate hearth (which I know is a reason some people keep the fireguard).
They're pretty sensible, I've kept it more to stop them falling into it if they're running about or being silly. Sometimes we have it going for large chunks of the day, so it can get pretty hot.
I'm not in a rush to remove it if it's still considered unsafe, just looking for thoughts really.