From a reader:
The Feast of Sts Peter and Paul is coming up this month which prompted me to order a Papal Flag to fly on that occasion. What is the custom for flying the flag throughout the year? Every Sunday, holy days, etc.? Technically, are we even permitted?
I don’t see why you couldn’t display a papal flag.
I don’t believe there is any special protocol to be observed, other than that which you should observe in regard any other flag flown near your national flag.