Take this for what it may be worth. Some years ago I was told this story by an elderly, retired Papal Ceremoniere or a Master of Ceremonies who (according to him) was present at the event about to be recounted.
You probably know that in the traditional Roman liturgical calendar the mighty feast of Pentecost had its own Octave. Pentecost was a grand affair indeed, liturgically speaking. In some places in the world such as Germany and Austria Pentecost Monday, Whit Monday as the English call it, was a reason to have a civil holiday, as well as a religious observance.
The Monday after Pentecost in 1970 His Holiness Pope Paul VI rose bright and early and went to the chapel for Holy Mass. Instead of the red he expected, there were green vestments laid out for him.
He queried the MC assigned that day, "What on earth are these for? This is the Octave of Pentecost! Where are the red vestments?"
"Santità," quoth the MC, "this is now Tempus ‘per annum’. It is green, now. The Octave of Pentecost is abolished."
"Green? That cannot be!", said the Pope, "Who did that?"
"Holiness, you did."
And Paul VI wept.