Her birth index:

First name(s)         Margaret G
Last name             Todd
Birth quarter         3
Birth year            1938
Mother's maiden name  Lys
District              Sevenoaks
County                Kent
Country               England
Volume                2A
Page                  1659
Record set            England & Wales Births 1837-2006
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No births found with a surname of Muggleston and a mother’s maiden name of Lys, not even for the whole wide world!
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In 1961 she was on a boat going to Singapore:

First name(s)             Margaret G
Last name                 Todd
Gender                    Female
Birth year                1938  }
Birth day                 21    } Which accounts for birth registration in Q3 of 1938
Birth month               6     }
Marital status            S
Occupation                Government Official
Departure year            1960
Departure day             7
Departure month           4
Departure port            Liverpool
Destination port          Singapore
Destination               Singapore
Country                   Singapore
Destination country       Singapore
Ship name                 Pyrrhus
Ship master's first name  H E
Ship master's last name   Wood
Ship destination port     Far East
Ship destination country  Far East
Number of passengers      0
Record set                Passenger Lists Leaving UK 1890-1960
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And I have found this address for her initial in NZ:

Muggleston M G
64 A Selwyn Road Cockle Bay Manukau City 2014
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Their marriage index:

First name(s)       Margaret G
Last name           Todd
Marriage quarter    3
Marriage year       1961
MarriageFinder      Margaret G Todd married one of these people
                    Geoffrey A Muggleston
Spouse's last name  Muggleston
District            Maidstone
County              Kent
Country             England
Volume              5B
Page number         1560
Record set          England & Wales Marriages 1837-2005
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