u/sofaglasses

This fact, that has been listed on various wiki sites and youtube biographies, is one that has never been mentioned in either the book or the movie. It's been driving me nuts trying to figure out where this information is from.

If there isn't a concrete source, my guess is that his birthday was originally listed as " 1st-23rd October" or something (as it's mentioned that his birthday is in October, and that he's a libra, so the range would have to be somewhere in October within the libra period), and someone misinterpreted that as JUST "23rd October" and it was never corrected.