Nope! Just decided to be a disappearing asshole for 36 hours and come back like nothing happened.
edit: thanks to all for the different perspectives. he is fixed, has all of his shots, and has his own temperature contolled kitty condo (aka the laundry room) that we put him into every night. we have a pretty good network of neighbors and pieced together his activities via security cameras. he's a mouser for sure and that is his job until he decides to retire.
Does it really need to be researched and peer reviewed before the fact that your cat, allowed outside, will be an invasive species that will kill small game animals that wouldn't otherwise have been killed, and that that is one of many reasons to keep it indoors?
Yes, if there are few enough, the impact won't be consequential, but humans making decisions assuming such things is why our streets are covered in cigarette butts and why we have to have trash cans along forest trails.
Even if the situation in the UK is fine, just that idea in itself can cause things to quickly become not fine, as a thousand people can each think to themself "one more cat won't be a problem" while together adding a thousand cats to the environment, not one.