Hi Pipester - thats from FreeBMD (
http://freebmd.rootsweb.com )
Nells source is a local transcription of the Birth Index from IOW Registry Office(s) --
http://www.isle-of-wight-fhs.co.uk/ its strange that it doesnt have the one I found in the GRO Index ...... the local ofice would have submitted their records to the GRO, so the original should be there for the IOW FHS transcription ...
I found a family of Ranns in 1851 father George, mother Harriette - with an 1840/1 daughter transcribed 'Janes' - but the image wasnt clear ... however no JANE was registered at all .....
keep us posted with the content of the Birth Cert ....

Added - section from a search for 'RANN' in the above site produces:-
Name- -Approximate Date of birth- -Other Surname(s)- -District Reference 1 GRAY, George 1840 RANN Godshill G2/P6
2 RANN, Jane 1840 BLOW Newport N2/P94
3 PAYNE, Harriet 1840 RANN Ryde R3/P8
So Jane Rann is there in the Local Register, but not in the GRO - I wonder if a correction was made after a quarterly submission ?