You make it sound so easy sadly that is not the case.

If I call Millie back quite often the other dog then proceeds to chase after her so I can't get her back till the owner gets their dog back.

If she is on the lead and is chased its very unpleasent because quite often all the owner does is yell at their dog while im left with my dog who by now is scaired of the other dog. This is were leads fail as a source of controll. If a big dog charges at a little dog on a lead reguardles how well trained they are it will create a nasty experience.

A greyhound type dog once chased her down four times while she was trying desperately to get back to me and pinned her and rolled her. The owner had a lead and and I was yelling at her to leash her dog as hers was hurting mine with its boistress behaviour.
It took ages for her to get over and she just walked off without so much as a sorry and I was almost in tears after that because I felt so angry. I am so glad Millie was not on a lead as she would have been much worse off.

I feel so sorry for poor Millie, my Mollie is very nervous of bigger dogs and we have had problems like that too. Really upsetting and leaves her more scared than she was before. I would say though a lead is good because then I can use my stick or body to get between her and the offending dog. If I had to get to her first it would be worse for her I think.