Hi,
I haven't actually asked Debra how she conducted her research for that info, or what resources she uses. But ... if you want to use NSW BDM online - marriages index,
My own notes say volume 41 is St James in around 1854-55 Likely that note comes from the NSW State Archives guide. NSW BDM webpage gives you the Early Church Codes, and CJ is St James C of E.

So, there's two main options that immediately come to my mind. Either use the Search by number only (so say start around 1000 and 1854) or use wildcard rather than the search by number option...
* for groom family name
01/12/1854 to 31/03/1855
CJ for district
and with plenty of patience, wade through each page of the index results, after clicking on the heading 'registration number' and read the first few digits of each, to see if there's any missing from the sequence ...
Hope that makes good sense, if not, please send me a PM and I will take some screen shots and email them to you.
JM