"The alarm was raised by a member of the public about 11am."

As an electrician, who has installed several security systems... why wasn't the electric fence tied into an alarm system? It's not that hard, farmers even have it installed in case their fence gets knocked down by a falling tree branch. The last thing you want is a herd of cows or horses loose. You'd think the last thing a zoo would want is an escapee oranguatan, but obviously they don't care the few hundred dollars it would cost to secure an exhibit that probably cost over a hundred thousand dollars.

Severe proof that the animals are not given enough mental stimulation in a zoo.

Yes - my first reaction was "Why don't they give her something interesting to do?".

Well, we know that many primates in the zoo are addicted to nicotine. Perhaps the nanny-state zoo administrators forced her to quit cold turkey "for her own good."

I'd McGuyver an escape attempt myself if my boss put an electric fence between me and a pack of smokes.

I doubt that would have held her - seems like she wanted to explore the area outside of her cage. I would too, if I was in a zoo.