IIRC, the area was not wired, precisely because people feared an electrical fault (short) might start the centuries old wood on fire.
A cigarette? I would love to have a dollar for every burn mark I have seen in counters to tables to bars, all the result of a cigarette landing on sometimes very well seasoned (over a century old) wood. Not one of those instances have ever led to a fire. It just isn't hot enough for the wood to reach flash point. (Think of starting a campfire, you need small stuff to get the big stuff to burn, unless accelerants are used).
Before all the chemicals were added to American cigarettes to keep them from continuing to burn if they were just sitting, you could tuck one in a matchbook and the matches would light when the cigarette burned down, like a timer, but even that doesn't work here any more.
Not sure if French cigarettes are similarly treated.
Even then, they had to have something to light, like rags, paper, or something soaked in fuel. Yes, that could be accidental, but who would be smoking up there, anyway?
