Japan
sake of public safety
I see what your did there!
Everyone has a mate who won't stop droning after a few bevvies – and the Japanese government clearly thinks the activity is dangerous enough to be outlawed. Today, among other restrictions clapped on UAV enthusiasts, the country approved penalties for anyone caught drink-droning with kit weighing more than 200g – including a …
Same goes for swimming, especially in natural waters that could be hiding obstacles. Or water that's too deep.
(Bought a new house last month and the pool goes to 10 feet. It's weird swimming in water over my head again that's not a natural lake with dirt/sand/mud bottom or steady wave action; haven't been in that situation since I was in high school. If I'm going to drink, I'll find a good floatie or stick to the shallow end, not just dive/jump in.)
According to this non-contemporary report there could have been a few hundred of them...
https://sussexwildlifetrust.org.uk/news/gatwick-airport-all-abuzz-with-new-arrivals
The rumour could have been started by the baggage-handlers as they didn't relish the prospect of 40 to 50 thousand workers coming in to take their jobs.