Latest on the Black Family Tree - Bellatrix Born in 1951

[Amanda]

OK so it's almost canon that Bellatrix Black was born in 1951.  A 
couple of people who were lucky enough to be at the viewing for the 
auction of the Black Family Tree, have made notes on what they saw. 
The Lexicon is reporting.

So, this means Bella is 8 years older than Snape, and unless JKR is 
about to shift the date of the Marauders and Snape birth, there is no 
way Bellatrix could have been at school with them. 

Someone is mistaken: Sirius in his `Gang of Slytherins' statement or 
JKR in her dates? And in actual fact they are the same person, but who 
is going to be taking the blame, I wonder?  

Mandy