Hi Karro, Leslam jus beat me to it!
3964 & 16883 are sequential numbers for binterrments in the cemetery. Richard was the One thousandth, eight hundred and fifty fifth person to be interred.
The Burial Registers start with the first one (No.1) and continue onwards.
Regretably, Warstone Lane Secretaries, have overv the years been a little lax in the recording. many Burial plots are not listed - they presumably knew at the tiome, and that all they were worried about - or they had additional records - now lost - probably in Diocesan offices (being Church of England).
The existing staff have no historical knowledge of the cemetery, and I cannot find a plan of the catacomb layout at Handsworth (Bishop of Worcestrer's office has been suggested).
All we do know is that most of the 'doors' you see in the catacombs are entrances to 9' x 6' box rooms - very much like self storage facilities nowadays. A drawing of one in the lower level at key Hill shows 3 shelves making 4 rows of 3 coffins - 12 in all.
Although designed for families, the take up was not great, and they were used for Public internments. Once built, they did not have to be dug out for use every time someione had to go in.
At present, without a good map of and layout plan, etc - there is almost no way of knowing exactly who is where. There are catacombs inside and some were under the South Cloister of the church.
Maybe one day we can Time Team to open up and investigate! Until than we can only say they are somewhere within.
Leslam has posted a pic of the catacombs, I'll see if I can find it.
Brian