A craze that began in the United States, the "killer crown" craze is "sweeping Britain", as reported by ITV News. Their report outlined a number of incidents in which people dressed as clowns had appeared aggressive or threatening towards members of the general public across the UK. Likewise, the BBC News also reports that "police in Scotland have warned that action may be taken against people who take part in the [...] craze". Among other news distributors, the Birmingham Mail -  a local tabloid newspaper for Birmingham - and Metro also reported regarding the craze and various sightings of these "clowns". 

I think it's interesting how a story that seems so sensational and left field is being reported by respected news sources such as the BBC which highlights how seriously authorities and the public are taking the craze.

The number of reports regarding this so-called "craze" also enforces the idea that it is an issue of national security, however this is without there having been any reports of physical harm or violence - this suggests that those partaking in the craze could be labelled as terrorists, in the literal sense of the word.