"Purple Airway" were the norm. I got a rollicking for not inputting a Royal Flight Plan correctly.
The RPL was from Newcastle to Northolt. NO Airway [then] between NEW and Pole Hill [joining airways]. In the ATC computer we used a "tailoring symbol" [ ./. ] so the a/c was zero timed to Pole Hill. What I SHOULD have done was to use an "En Route" symbol [ .. ] so that the NEW..POL time was calculated.
Auntie Betty duly leaves NEW and is departed in the computer.....
unfortunately it takes the departure time as the ARRIVAL time at POL...... in an Andover, about 27 mins. London Centre went ballistic! Fortunately the error was [very] quickly corrected.