Peter Wright (1987, pp. 70-71) recounts the tale of a delicate MI5 operation to bug an embassy in London:
The house next door was temporarily empty, and A2 obtained access to install a series of microphones. Hugh Winterborn and I led a team of twelve officers from A Branch. Silence was imperative because we knew that the target premises were permanently manned near the party wall. I made a tremendous fuss insisting that everyone remove his shoes to avoid making noise on the bare floorboards. We worked nonstop for four hours in the freezing cold. All the floorboards on the first floor had been raised and I was patiently threading the cables along the void between the joists. After a time one of the leads became tangled on a split joist. Unable to clear the obstruction by hand, I began to ease myself down until one foot was resting on a masonry nail sticking out from one side of a joist. Just as I was inching toward the tangled cable, the nail gave way, and I plunged through the ceiling below. A large section of ceiling crashed fourteen feet to the floor below, reverberating around Portland Place like a wartime bomb. The noise and dust subsided, leaving me wedged tightly up to my waist in the hole in the ceiling. For a moment there was total silence.
“Good thing we removed our shoes,” quipped Winterborn dryly as laughter began to echo around the empty building.
– Peter Wright (1987, pp. 70-71), Spycatcher. Viking Penguin, Inc.