His birth index:

Name:                       Mother's Maiden Surname:
HENNELL, CHARLES JAMES      DRUMMOND  
GRO Reference: 1912  S Quarter in EASTBOURNE  Volume 02B  Page 96
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This birth is confirmed by his entry in the index, with his parents, to the 1921 census.  They were in Eastbourne, Sussex area.

There are two Charles James Hennell births around 1912:

Birth Year and Place
1906  Bury St Edmunds, Suffolk
1912  Eastbourne, Sussex
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In 1939 he was, presumably, lodging at 8 The Quadrangle, Welwyn Garden City, Herts:

                                                          Marital  Schedule
First name(s)  Last name(s)  Birth date  Sex  Occupation  status   Main sub
Lena M      McGredy    18 Jun 1892  F  Unpaid Domestic Duties            M  334  1
Olive O     Latchmere  18 Jul 1896  F  Wages Clerk Radio Factory         W  334  2
Kitty M     McGredy    19 Feb 1915  F  Shorthand Typist                  S  334  3
Charles J   Hennell    22 Jul 1912  M  Export Clerk (Abrasive Wheel Ma)  S  334  4
Clifford L  Godfrey    23 May 1913  M  Draughtsman Steel Equipment       S  334  5

1939 ref: RG101/1646D/009/1
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In his aunt, Eileen Amy Powys Hughes’s, will these two were named as her Personal Representatives in the London Gazette of 9th July 1970, p. 7664:

  Charles James Hennell and Peter Robert Hennell

Might Peter Robert be a brother?  Wait for her will to arrive.  He could be Charles’ son as he may be the one born in Hatfield in 1944.  His mother’s maiden name was Hughes which just happens to be the maiden name of the lady that Charles James married in 1940.
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There is a marriage for a Charles J Hennell in Hitchin in 1940.  Him?  This might need a marriage certificate.  (See previous sentence.)
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This death index has the same birth date as above in 1939:

First name(s)  Charles James
Last name      Hennell
Gender         Male
Birth day      22
Birth month    7
Birth year     1912
Death quarter  4
Death year     1974
District       Hatfield
County         Hertfordshire
Volume         10
Page           0383
Country        England
Record set     England & Wales Deaths 1837-2007
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The evidence for his clearly being the son of Gladys and the father of Peter Robert:

In 1940 he married Anthea Molesworth Hughes.

In 1944 his and Anthea’s son Peter Robert was born.

1949 he was included with his mother as Principal Representatives for his father’s probate.

In 1953 he and his wife Anthea Molesworth were the Personal Representatives for his mother’s probate.

In 1970 he and his son Peter Robert Hennell were Personal Representatives for his aunt Eileen Amy Powys’ probate.

This will now be entered up and the three wills and his will have been ordered.
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His probate index:

1975
HANNELL [ sic ], Charles James of 24 Reddings Welwyn Garden City Herts died 17 November 1974  Probate Ipswich 27 February £21162 751015085C

Will ordered on 22 Mar 2022.  This was rejected, possibly because of the Hannell/Hennell confusion.  So ordered again on 1 April 2022.
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Their marriage index:

First name(s)       Charles J
Last name           Hennell
Marriage quarter    1
Marriage year       1940
Marriage Finder     Charles J Hennell married one of these people
                    Anthea M Hughes
Spouse's last name  Hughes
District            Hitchin
County              Hertfordshire
Country             England
Volume              3A
Page number         3569
Record set          England & Wales Marriages 1837-2005
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