hi bob
your experiences with millie sound very similar to those that we have had with a certain 12-month old lad snoozing beside me at the moment.
his recall has been completely hit and miss for the past few months and, whilst we are putting a lot of his attitude down to adolescence, we are also working on it consistently.
whistle training is going slowly, primarily because barkley really isn't food orientated and is most definitely going through a phase at the moment of looking up to see what we want, evaluating whether or not to return, and quite often deciding not to and carrying on with whatever he was up to beforehand!
consequently, i am trying to avoid letting him off in environments where i have to be sure of his return. this way, i don't have to call him as often and he doesn't have the same opportunities to ignore me! (if that makes sense) on the whole, when we get to the end of a walk he is worn out enough to come back to me quite happily. i definitely wouldn't let him off in crowded places or parks until i can rely on him totally in more secluded areas first. the long line is something that we will try if whistle training doesn't work.
as an aside, what do people recommend that you do when your dog does eventually come back after a looong period of being evasive and quite clearly choosing to ignore his owner? obviously i would never shout at or reprimand barkley in any way (that would clearly make him wonder what the point in returning was) but do you still praise highly (bearing in mind that he quite often ignores the piece of chicken being held out to him anyway) or make it fairly clear that you are not terribly impressed by silently putting him back on lead and walking on? just curious as i am otherwise not too sure how to make barkley realise that his dithering about is not exactly what i had in mind when i called him!