No record can be found on FindMyPast for the birth of any Kathleen Calgie.  Alternatively, this might be a second marriage for her, but I cannot find any marriage between a Kathleen and a chap surnamed Calgie.

Could this death index be for her?

First name(s) KATHLEEN
Last name MELLON
Gender Female
Birth day 22
Birth month 12
Birth year 1916
Death quarter 3
Death year 1998
District Stockton
District number 3501B
Register number B6
Entry number 277
Date of registration mm/yy 0798
County Durham
Country England
Record set England & Wales Deaths 1837-2007

If it is her, there is no surname of the 80 odd Kathleens in the 1939 Register with that birth date.

A search of Scottish births from 1910 to 1945 produces two Kathleen Calgie births, curiously both for the same year:

Surname Forename Gender Year Ref RD Name
CALGIE KATHLEEN F 1934 644/15 238 Hutchesontown
CALGIE KATHLEEN F 1934 644/8 682 St Rollox

There are no Scottish marriages for a Kathleen Calgie.
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Their marriage index:

First name(s) KATHLEEN
Last name CALGIE
Marriage quarter 4
Marriage year 1960
KATHLEEN CALGIE married one of these people
Francis Mellon
Spouse's last name Mellon
District Durham South Eastern
County Durham
Country England
Volume 1A
Volume as transcribed 1A
Page number 1320
Record set England & Wales Marriages 1837-2005
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