Under section 3(1) of the Public Order Act 1986, affray is defined as the use or threat of unlawful violence by one person towards another, where such conduct would cause a person of reasonable firmness present at the scene to fear for their personal safety. This means that the offence can be committed by a single individual, as long as their actions or threats create a situation where a bystander would feel threatened. It does not require multiple persons to commit the offence. 

Key Point: The Public Order Act 1986 outlines that affray can be committed by a single person using or threatening unlawful violence, provided it creates fear for personal safety in a reasonable bystander.