Her probable birth index:

First name(s)         CHRISTINA M
Last name             ZAMBRA
Birth year            1931
Birth quarter         3
Mother's maiden name  Mann
District              Godstone
County                Surrey
Country               England
Volume                2A
Page                  436
Record set            England & Wales Births 1837-2006
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Last seen on any record in 2002-3 in King's Lybb electoral roll.
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Did she marry a Smith in 2004?

First name(s)        CHRISTINA M
Last name            MINSHULL
Marriage quarter     2
Marriage year        2004
Registration month   5
MarriageFinder       CHRISTINA M MINSHULL married one of these people
                     Peter Smith
Spouse's last name   Smith
District             Chester & Ellesmere Port
District number      340
County               Cheshire
Country              England
Page number          0459
Entry number         108
Source code          C51
Record set           England & Wales Marriages 1837-2005

And did Christine Marjorie Smith die on 5 Nov 2017?

Surname  First name  Date of probate  Probate number  Date of death  Document type  Registry
SMITH    CHRISTINA MARJORIE   15 December 2017  5285942  05 November 2017  Grant and will  Oxford

For £1.50 I thought it a good punt to order this will.  It might mention her children.

It is fairly definitely not her.  She records four Smith children in her will and with names very different to Christina Minshull's children.
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She could, of course, still be alive, aged 88 or so.
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First name(s)        MERLIN T
Last name            MINSHULL
Marriage quarter     1
Marriage year        1956
MarriageFinder       MERLIN T MINSHULL married one of these people
                     Christina M Zambra
Spouse's last name   Zambra
District             Westminster
County               London
Country              England
Volume               5C
Page number          839
Record set           England & Wales Marriages 1837-2005
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