Humanism in the age of Henry VIII. London ; Dover, N.H. : Croom Helm, 1986 (OCoLC)795302915: Named Person: Henry, King of England; Henry, King of England; Henry, King of England: Document Type: Book: All Authors / Contributors: Maria Dowling
Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM). It is also known as Z time or Zulu Time.
Both are time zones. GMT is Greenwich Mean Time, the official time at the Royal Observatory in Greenwich, England. UTC is Universal Time Coodine', or in English Coordinated Universal Time.. For practical purposes it is pretty much the same thing, but it's more acceptable around the world because it doesn't sound quite so British.