Just to update you - It was staring me in the face - In the base class of my usercontrol I added a property of type IRefreshForm - then overrode the OnLoad event with this

public IRefreshForm RefreshForm;

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
        
    if this.ParentForm is IRefreshForm)
    {
        this.RefreshForm = (IRefreshForm)this.ParentForm;
    }
}

works like a charm