I don't get this. It's clear the families assertion that he couldn't leave the area undetected is driven in part by the presence of the camera on the back of the Cornhill shopping center. So they must have viewed the area as including a short stretch of Short Backland street and the second loading bay, hence Nicola being keen to have the properties opposite searched. So it strikes me as a little odd to call BS on something that is basically our incorrect assumptions based on incomplete information (which has now been clarified). Unless of course it's been demonstrated that you can walk out of the wider area undetected of course, in which case it would be great if someone could explain how the CCTV pictures demonstrate that.
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Apparently sectored antennas commonly come in 60, 90 and 120 degree versions (per Wikipedia), so given we know that the recycling depot is a possibility, we can probably rule out the southern 120 degrees from Midsummers map, but not much else. Damn.