PM

PM was a period of the day opposite to AM. (TV: The Sontaran Stratagem) 11:57 PM (23:57) was three minutes to midnight. (TV: The Pyramid at the End of the World)

History
In the 1950s, hours of television broadcast in the United Kingdom were strictly limited by the British government, and each evening's broadcasts from Alexandra Palace ended between 10.30 and 11pm with the National Anthem. (PROSE: The Time Traveller's Almanac) What's My Line? was hosted by Eamonn Andrews and ran from 1951 to 1963, each Sunday at 8.30pm. (PROSE: The Time Traveller's Almanac)

According to a timeline of the Dummy Massacre posted on the Who is Doctor Who? website in March 2005, the London Eye became a "wheel of fire" at 7.08PM, the killer dummies began attacking at 7.09PM, and they began to die at 7.16PM. (PROSE: Dummy Massacre)

The newly-regenerated Tenth Doctor planned to take Rose Tyler to the planet Barcelona on 6 PM of a Tuesday in October 5006, his previous incarnation having told her that she would've "love[d] it" immediately prior to his regeneration. However, he cancelled this to take her back home to the Powell Estate on Christmas Eve 2006. (TV: Born Again)