Yep. They grade these things according to the nature of the report, ranging from "local standby" to "full emergency" to "aircraft crash imminent".
I worked at LGW for three & a half years and attended plenty of the first two, and none of the last (thankfully). It's usually stuff like smoke in...
These things happen far more regularly than you'd think. The turnarounds are generally precautionary and it's extremely rare for there to be problems landing. Most of the time, the passengers are none the wiser, as the issue only arises as the aircraft is approaching its destination airport. It...