Darkrenown said:
That can't be quite true, I've had the opium trade fire twice in one session as the UK without loading. It seems reloading does help though.
It is perfectly possible for "Opium Trade" to fire twice in one session although I doubt it is fired more than once by the random trigger.
There are three ways for the UK to get its "Opium Trade" event (6938):
1 & 2) China's "Opium Trade" event (12500) triggered by random or explicitly "The Treaties of Beijing" (12516)
3) China's "High Commissioner Corrupted!" (12502)
The third case is nothing to do with China's "Opium Trade" event and therefore has not bearing on the persistent/random debate. It simply looks the same to the UK.
Cases 1 and 2 however are part of the debate.
persistent = yes definitely allows an event to be fired several times. It can be explicitly triggered by several different events. However, it appears that the random element can only trigger a persistent event once unless it is reset by a save and load.