I've found Mary's sister, Eliza Ann Wheatcroft's 1855 St Pancras marriage to Edward Moore (bachelor, commercial clerk, father John Moore gentleman)

Eliza Ann's father William Wheatcroft brass founder.

Do you have a subscription to Ancestry ?

From the index:

about Eliza Ann Wheatcroft
Name: Eliza Ann Wheatcroft
Spouse Name: Edward Moore
Spouse Age: Full Age
Record Type: Marriage
Marriage Date: 18 Feb 1855
Parish: St Pancras Parish Church
County: Middlesex
Borough: Camden
Father Name: William Wheatcroft
Spouse Father Name: John Moore

******************************************
ht tp://search.ancestry.co.uk/search/db.aspx?dbid=1623

(close the gap in ht tp)

Jean C