Thanks for everyone's continued feedback and support - you have all been very helpful
I thought I should provide a bit more detail about Newt which might help deciding how best to deal with her tendencies (now and in the future).
I've been walking Newt for about 3 weeks now, averaging about 5-6 walks a week, ever since the 2nd incident below.
She had previously 'escaped' twice before since I adopted her - once before the litter arrived, and once after. The latter incident caused me to drive to an emergency pet hospital to pick up some KMR in the middle of the night as I had no idea when (or if) she was coming back - the kittens were only 5 days old at this time. Fortunately, she came back around noon the next day. This is when I decided I wouldn't let her out of my sight. Hopefully she didn't get knocked up again during that particular escapade.
I've met people around the neighbourhood and been told a lot of stories about this particular cat during her walks. Apparently, she had a previous owner somewhere in the area, or so I'm told (one strikes up the most interesting conversations with strangers when walking a cat). So it may certainly be true she had another home (or two) previously.
Back to the present... I haven't walked her the past two days. She complained a lot more last night, but nothing close to her worse tantrums (I'd rate it around 3/5 on the Newt complaint scale, easily 1/5 the night before).
My next question is, is it better to try and stop her walks cold turkey, or should I just gradually ease her off the walking routine? If I can manage one walk a week without her complaining, I'd be pretty happy with that.