Her baptism:

First name(s)           Ellen Mary
Last name               Causton
Gender                  Female
Baptism year            1832
Baptism date            28 Nov 1832
Baptism age             25 Oct 1832
Residence               St. Botolph Aldersgate, London, England
Place                   St Botolph Aldersgate
County                  London
Country                 England
Father's first name(s)  Thomas Henry
Father's last name      Causton
Mother's first name(s)  Frances Hester
Mother's last name      -
Record set              England Births & Baptisms 1538-1975
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Thanks to Ancestry the image of her baptism register has been found, transcript by me:

“                          Page 56
“BAPTISMS solemnized in the Parish of St Botolph, Aldergate, in
“     the Year One Thousand Eight Hundred and Thirty Two
“. . . .
“When Born:           Oct 25th 1832
“When baptized:       Nov 28th 1832
“No:                  4456
“Child’s Forenames:   Ellen Mary D of
“Parents’ Forenames:  Thomas henry & Frances Hester
“Parents’ surname:    Causton
“Abode:               Charter House Square
“Profession:          Clerk
“Celebrant:           T H Causton
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Her death aged 16:

Name:                     Age at Death (in years):  
CANSTON, ELLEN  MARY      16  
GRO Reference: 1849  M Quarter in SAINT PANCRAS  Volume 01  Page 274

But the image on the original index clearly says Causton.  Told ‘em.
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