His birth index:

Name:                          Mother's Maiden Surname:
DEWHURST, HUGH  LITTLETON      BROUGHAM  
GRO Reference: 1909  J Quarter in BUCKLOW  Volume 08A  Page 207

His baptism:, transcribed by me from an image of the register:

Place:        Parish of Oughtrington in the country of Chester
Year          1909
Date:         28 May 1909
No:           20
Name          Hugh Littleton
Parents:      Gerard Powys and Mary
Surname:      Dewhurst
Abode:        oughtrington Park
Profession:   Merchant
Off MIn:      ? ? Howson
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the first two children can be found with a mother’s maiden name of Dewar.  But the reported (Peerage.com) Fiona, born in 1942, cannot be found on any index, not even a British overseas registration; she was reported to have married a David Alexander Whitaker, but no record can be found of such a marriage, not even a marraige between any (female) Dewhurst and any (male) Whitaker; they are reported to have had a daughter Lucy B Whitaker, but the English Lucy Whitaker birth in 1971 has a mother with a maien name of Barry.

Let’s try Scotland’s People:

There is a Fiona Mary Dewhurst born in 1943 but no maiden names included.  But finding the marriage with ‘Fiona Mary’ makes it more likely this is her:

Surname   Forename    Gender  Year  Ref      RD Name
DEWHURST  FIONA MARY  F       1943  685/6 4  Newington

And Bingo, There is a marriage:

Surname   Forename    Spouse Surname  Spouse Forename  Year  Ref       RD Name
DEWHURST  FIONA MARY  WHITAKER        DAVID ALEXANDER  1968  387/ 192  Perth

And for the bierth of Lucy B Whitaker:

Surname   Forename      Gender  Year  Ref         RD Name
WHITAKER  LUCY BELINDA  F       1971  685/5 2084  George Square

And for the marriage of Lucy Belinda to Alan J Normile in 1999:

Surname   Forename      Spouse Surname  Spouse Forename  Year  Ref       RD Name
WHITAKER  LUCY BELINDA  NORMILE         ALAN JAMES       1999  390/ 179  Perth

And this is said to lead to the births of Ben, Sophie and Tom:

Surname   Forename       Gender  Year  Ref         RD Name
NORMILE   BENJAMIN HUGH  M       2003  390/ 117    Perth
NORMILE   SOPHIE EMMA    F       2006  390/ 382    Perth
NORMILE   THOMAS DAVID   M       2010  450/ 2      MILNATHORT


(I would never have found all that without the help of Peerage.com)

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From FindMyPast:

“IN LOVING MEMORY OF
IRENE MARGARETTA DEWAR
BORN 21 JULY 1908
DIED 27 APRIL 1988
WIFE OF
HUGH LITTLETON DEWHURST
BORN 28 APRIL 1909
DIED 27 DECEMBER 1992
OF
DUNGARTHIL DUNKELD”

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The transcription by FindMyPast is:

First name(s) Hugh Littleton
Last name Dewhurst
Birth year 1909
Death year 1992
Cemetery Aberdalgie Church
Burial ground Aberdalgie
County Perthshire
Country Scotland
Transcription In loving memory of Irene Margareta Dewar 21.7.1908 – 27.4.1988 wife of Hugh Littleton Dewhurst 28.4.1909 – 27.12.1992 of Dungarthill, Dunkeld - - Emily Rose Normile 27.5.2009. Always loved, never forgotten
Record set Scotland Monumental Inscriptions


Note that their gt-grandchildren were Normiles, but none of those forenames.

An alternative though is that Emily Rose Normile was remembered in the grave, or even buried here, but no death of such can be found in Scotland.
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Their marriage index:

First name(s)       HUGH L
Last name           DEWHURST
Marriage quarter    1
Marriage year       1934
MarriageFinder      HUGH L DEWHURST married one of these people
                    Irene M Dewar
Spouse's last name  Dewar
District            Chelsea
County              London
Country             England
Volume              1A
Page number         716
Record set          England & Wales Marriages 1837-2005
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