David, here's the reply I got this morning from my email (not the feedback form):
Thank you, for contacting us. I am sorry your December issue arrived to you with loose pages. We have highlighted the issue to our production department for investigation. A replacement copy will be sent out in the post to you today. You can expect it shortly.
Please accept my apologies for the error and any inconvenience this may have caused.
Which all seems hunky dory.