I just googled the old parentheical statement and I realise I've been doing it for years without realising it. That's probably because they weren't called that when I was taught English or maybe they were and Mrs Wilkinson forgot to mention it. Either way, I'm still not keen on breaking up the sentence up with dashes. And while I'm on the subject and my high horse I think that "breaking up the sentence" is better than the "setting off the sentence" that the editor chose to use.
Okay, best get down before I get saddle sore.
BTW since the last time I was here Nice has moved on by a mere 200 words or so (who am I kidding? Its more like 100) and I've spent the rest of the time looking into getting a better quote for my car insurance.