An Elizabeth Elstob death in Biggleswade registration district was registered in 1868. Whether it's
your Elizabeth, another Elizabeth Elstob, or a transcription error for Elston, is yet to be determined. Probably easiest to order the death certificate.
Interesting that in 1851 there's an Elizabeth Elstob visitor 20 born London staying at the Crown Inn, High St, Biggleswade, with the Marsom family. See a BLARS catalogue item at
http://blars.adlibsoft.com/wwwopac.exe?DATABASE=catalo%3Egroups&LANGUAGE=0&DEBUG=0&BRIEFADAPL=../web/adapls/wwwreq&DETAILADAPL=../web/adapls/wwwreq&%250=800001497&LIMIT=50 where presumably it's this Elizabeth Elstob who's mentioned, but for the life of me I can't work out her connection to the Marsom family, and indeed if she's connected to your Elizabeth Elstob. But it's an almighty coincidence that out of half a dozen Elizabeth Elstobs in England two of them should pitch up in Biggleswade, which is not exactly the centre of the universe, notwithstanding that johnP and I both went to skool there!
David
Might have worked out the Biggleswade Marsom/Elstob connection! John Elstob married Elizabeth Marsom on 12 Nov 1828 at St Bartholomew the Great London, where they baptised a daughter Elizabeth on 17 Oct 1830. This appears to be the 20 year old living with the Marsoms in 18
4151
(good spot John!) So what odds that the death in Biggleswade in 1868 was her mother, Elizabeth Elstob née Marsom, rather than Elizabeth Elstob née Quenby? An Elizabeth Marsom was baptised in Biggleswade in 1803