Air conditioning...

... that boldly goes where others fear to tread. We had rather a lot of fun finding the two hidden vents, vaguely described by the previous owner as being above the doors. They weren't. My very clever other half had the wonderful idea of taking pictures inside the shaft from the existing vent to work out where they were.

As you can see from this inside view, the likelihood of air loss here was high, and it turned out that spaces between walls and above cupboards were being rather well ventilated! Here's the outside view of the other vent. One of the vents was filling this space above the cupboards!