james: UTC (or GMT) is known as "zulu", which is the standard ICAO and ITU phonetic for the letter "Z". The zones start from "Alpha" in Western Europe and continue eastward. Eastern Standard Time is "Romeo". Since there are 24 time zones, there are enough letters with two to spare. Based on the sequence, GMT would otherwise have been "Whiskey", but it was declared to be "Zulu" to give it distinction.

And yes, I have one of those dumb pictures with my two feet straddling the prime meridian in the forecourt of the Royal Observatory.