If your bees were on a windy Welsh hillside they might benefit from having the inspection board slotted in for winter (or an empty super under the BB, or a solid floor) but in warmer Folkstone I don't reckon it's worth the bother.
Glad you posted the photo, which is the opposite of a windy Welsh hillside and shows the hive hemmed in by 6' fence panels and a eucalyptus. I'd be more concerned with loitering damp caused by a lack of airflow, and leave the board out.
In the end you must weigh up the options, follow your instinct and monitor. If you do put in the board, check it every so often: it may be covered with mouldy pollen, mouldy wax and other mouldy mould, in which case take it out.