Riddle and Grindelwald in 1945

[Matt]

No: HPFGUIDX 109038

--- Geoff Bannister wrote:
> The Chamber was re-opened in the autumn of 1992, Harry 
> first hearing the Basilisk in September and the first 
> petrification being on Hallowe'en night. If the 50th 
> anniversary is spot-on accurate, then the previous 
> opening was in the autumn of 1942; hence Riddle was in 
> the Fifth Year in 1942/43. So, if he went on into the 
> Sixth Form, he would have been in the Lower Sixth in 
> 1943/44 and the Upper Sixth in 1944/45 so he would be 
> just be on the point of finishing at Hogwarts or would 
> have just finished when Grindelwald was defeated.

The Lexicon has Riddle opening the chamber in 1941/42 and graduating
in June, 1944, based on the "official timeline" that appeared on the
CoS DVD and apparently was vetted by JKR.  Previously, the Lexicon
showed the later dates, based on the same calculation you used.  

There are a lot of "50 year" references in CoS, including at least one
that appears intended to be precise:

"The little book lay on the floor, nondescript and soggy. 'Well, we
won't find out unless we look at it,' [Harry] said, and he ducked
around Ron and picked it up off the floor.  Harry saw at once that it
was a diary, and the faded year on the cover told him it was fifty
years old."

(from Chapter 17, after they find the diary in Myrtle's bathroom).

Since it is a calendar year -- not academic year -- diary (Hermione
later flips it opens to January 1 when she is testing for invisible
ink), and they find it after the beginning of the spring term 1993,
that passage would appear to indicate that the diary was from 1943, a
date which supports your version of the timeline.  In order to be
consistent with the earlier dates, one would have to assume that
Riddle did not begin creating the diary until late 1942 (during his
sixth year), at which time he could have purchased (or been given) a
1943 datebook.

Then again, given that JKR has not always been absolutely precise
around dates and class years, it may be futile to look for perfect
consistency on this point.

-- Matt