Hi, I have just come across your post. Bridie is 20 months old, in the house she is quite a good girl but outside I can't let her off at all. For e.g. took her over the playing field today which is not secure, let her off and that was it, no matter how many times I called her back, she just took no notice. Why is it she will do it in the house but not out and pay no attention to me whatsoever, she won't even come back for a treat?! Is it too late to start whistle training at 20 months? I'm sure if I read through loads of posts I will probably find the answer, but, desperation has kicked in today!!