Hi, Having studied this cemetery,its history and its layout for my own purposes, I believe I can give you an idea of what and where you are looking for.
All entries in the registers that are available will be in either a 'paid' or an 'Unpaid for' register.
An "unpaid for" is more indicative of the very early years of the cemeteries existence.
That is to say the era 1856 -1895 when most 'public' burials took place at the Southern end of the site and were afforded by the Parish or "Guardians".
From about 1894 onwards there were two areas defined and allocated as being "public" areas at the Northern end of the site. Sadly it has to be said that these areas have also been subjected to much disruption since the 1940's and at least 60% of one such public area has been developed into housing by none other than the UK government in the guise of Her Majesties Prison Service, apparently breaking their own rules on development of such sensitive areas ?
It was the method of gravediggers in those days to follow a grid pattern, and so they would begin at a chosen corner of a field and would excavate what would be an ongoing trench to a depth of 8 feet minimum and in a straight line, this initial trench would be nominated as "A" and the first 6 foot of its length would become grave number 1 etc, ad infinitum.
Each would be backfilled in the order of (usually) two 'full grown' adults, followed by up to four junior adults (aged over 7years),and last would be infants and newborns. This would progress slowly along the chosen direction and each 'position' might take weeks to achieve the required 'density' of cadavers before it is finally "closed". A close study of the registers for some years especially around the early 20th Century reveals a very high infant mortality rate due to pandemics and disease and can account for as many as 32 names bearing the same grave reference number !
So to summarise, the reference number (O - 21)and date that you have can not get you to an exact location but could be approximated within 5-10 metres during a visit.
10/- of old £.s.d was the cost of burying an 'adult' (defined as being 7 years of age or older)and covered the simple wooden coffin and the gravediggers wages.
In 1911 this was just about affordable for most families and avoided the social stigma of being buried a "pauper" (There is no official classification of a paupers grave by the way).
It must be said that Cg does indeed indicate a 'common' grave and in most cases within this cemetery will have no visible identity whatsoever.
The Southern end of the site has given way to well established dense woodland now and is almost impossible to penetrate in some areas during the summer months.
Severe vandalism after its abandonment in the late 1960's also destroyed many memorials that did exist in those areas where they were afforded and where proper Section and Grave numbers were allocated and recorded.
BTW I believe it may have been my thread on Liverpool&SWLancs FHS forum that Victoria refers to!
