Mid-ceremony: somewhere around the offertory. St Patrick's Cathedral choir was in full voice performing something by Palestrina. The congregation was silent, some possibly dozing. Five hundred year old polyphony does that to you. The dean (or the deacon, I never know which is which), wielding an incense burner, was smoking the altar like a beekeeper calming his bees, and the chains of the incense burner were singing a soft metallic rasp.
He turned and swung the burner towards where we were sitting in the transept, and the indefinable aroma (perhaps the inside of a hundred-year-old cedar drawer used to store pipe tobacco in the library of a vicar who has given up smoking) of incense drifted across to greet our noses.
Palestrina's unearthly syntactical perfection was progressing along a sonic line unbroken by any harsh melodic, and I was marvelling that it was probably the most sublime sound ever created by man, beast or machine.
Then the siren went off.
It was a discordant, high-pitched whooping screech in half-second repeats, followed by an electronic voice, like the Lost in Space robot, intoning e-vac-uate! e-vac-uate! It stopped after about twenty seconds had dragged themselves across the tyranny of time.
Incredibly, the choir had carried on as if nothing had happened. Likewise, the archbishop, completely unruffled, had merely paused momentarily, cocking his unmitred head slightly, before ad-libbing to no-one in particular: 'New fire alarm installed this week: must be a bit sensitive!'