Heathrow Director:
Yes, unlike today's schedules of multiple daily departures at more or less regular intervals, in the 1960's, many routes ex-LHR (or LAP in those days) to continental European destinations would have one or two daytime departures and a night flight departing at some unearthly hour such as 2300, midnight, or even 0100 or 0200! I guess the night flights were scheduled to tap into the "low-fare market" of the day by offering special night tourist prices.
Living close to the BPK VOR in those days,we would get the domestic BEA Vanguards noisily climbing away from 10L or 10R departures, sometimes 3 or 4 in quick succession, and KLM Electras departing on 28L or 28R departures. Best sound of all were probably made by the various Eastern European IL-18's. Most exotic was an Areoflot TU-114 climbing away at very low altitude off 28L or 28R, must have been around 1965. A very rare bird.