Poison Gas Cloud

[Lightspeed]

If it came from a ship in the channel, it will be relatively easy to narrow down to the culprit. Ships in the channel are handled like aircraft coming into airports. They are logged and tracked in real time and that tracking is recorded. With known wind direction and strength, a back track can be calculated, isolating just a few vessels, maybe a single one?

This will have already been done, and follow up now quietly taking place.