Hhmm trying to find a marriage for Kemp/Petty and not coming up with anything.  However I seem to have found the marriage of Elizabeth's parents:-
George Kemp to Mary Ann Newman on 28 September 1834 at Minster in Sheppey, Kent.  Groom's residence given as Teynham.
So the Teynham fits there.
This appears to be Elizabeth's birth registration:-
KEMP, ELIZABETH       NEWMAN     
GRO Reference: 1840  J Quarter in FAVERSHAM UNION  Volume 05  Page 174
I've found Elizabeth's family in the 1841 census living at Blue House, Teynham, Faversham, Kent
Parents George and Mary and two older siblings Mary (1836) and George (1838).
Registration District  Faversham
Piece number   476
Book number   4
Folio number   22
Page number   6
In 1851 living at Barrow Green, Teynham, Faversham, Kent, now has four younger siblings.
Registration district   Faversham
Piece number   1626
Folio   566
Page   19
Well this is interesting.  Elizabeth is still with her family in the 1861 and still single.
I'm not finding any marriage between a Petty and a Kemp up to 1874.