m. (1) Mary Ann Comley, (2) Maria Winifred Shuttleworth, (3) Ann Amelia Florance
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Is he the "George H T Powys, formerly a clerk at the bank of England" in the 1881 census?   Looks very likely as the age is right.  If so he had a three sons and two daughters all around the age of 20 with him then, plus his wife.
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In 1841 this was almost certainly him with his first wife, but with no children:

Name Sex Age Birth Year Occupation Where Born

POWIS, George M 27 1814
POWIS, Marian F 27 1814

RG number: HO107 Piece: 732 Book/Folio: 13/7  Page: 6    

Registration District: St George Hanover Square Sub District: Belgrave
Enumeration District: Ecclesiastical Parish:

Civil Parish: St George Hanover Square Municipal Borough: Westminster
Address: Upper Ebury Street, South Side, St George Hanover Square, Westminster
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In 1851 he was listed under the surname of Ponys (I’ve sent in six corrections to FindMyPast):

Name  Relation  Condition  Sex  Age  Birth Year  Occupation Disability  Where Born

PONYS, George Hem Norman Head Married M  37  1814  Clerk Bank Of Beyland   Fawley, Buckinghamshire
PONYS, Maria Wife Married F 28 1823  Barton, Lancashire
PONYS, Alfred Norham Son M 3 1848  Brompton, Middlesex
LONGDON, Emily Servant Unmarried F 18 1833 House Servant  Pimlico, Middlesex

RG number: HO107 Piece: 1469 Folio: 404 Page: 19    
  
Registration District: Kensington Sub District: Brompton
Enumeration District: 10 Ecclesiastical Parish: Saint Marys West Brompton
  
Civil Parish: Kensington Municipal Borough:
Address: 2, Seymour Place, Kensington, Hamlet Brompton
County: Middlesex
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TFPL, Sep 2004, from Ancestry.com it looks like he had a second marriage:

Name Year Quarter District County Volume Page

Burr, George 1853 June Kensington Greater London London Middlesex 1a 27
Clift, Susan 1853 June Kensington Greater London London Middlesex 1a 27
Florance, Ann Amelia 1853 June Kensington Greater London London Middlesex 1a 27
Powys, George Henry Norman Toury 1853 June Kensington Greater London London Middlesex 1a 27
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Mar 2007, TFPL: Trudy Weaver with her painstaking BMD and census research has come up with this for Norman and his family:

  George Henry Norman Toovey POWYS

  Home Page | New Search | Individual | Pedigree | Descendancy | Login Birth† 1814† Henley, Oxfordshire†
Sex† Male†
Died† 1885† Croydon†
Person ID† I618†
Last Modified† 12 Mar 2007†
†
Family 1† Mary Ann COMLEY†
Married† 1831† †
†Children†  †1. Norman POWYS

Group Sheet† F308†
†
Family 2† Ann Amelia FLORANCE, b. 1823, Chichester, Sussex†
Married† Jun 1853† †
†Children†
†1. Florence C E POWYS, b. 1855, Brompton, Middlesex
†2. Arthur Edward POWYS, b. 1859, Chelsea, Middlesex
†3. Edmund Draper POWYS, b. Mar 1860, Chelsea, Middlesex
†4. Herbert Lilford POWYS, b. 1862, Brompton, Middlesex
†5. Letitia A POWYS, b. 1866, Brompton, Middlesex

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In 1861 he was a Clerk with the Bank of England, living at Kensington, St Mary Abbot with his new wife and daughter and two sons, ages 7, 2 and 1.
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In 1871 he was living at Tooting Graveney, still a clerk in the Bank of England, with his wife Ann A and their two daughters, aged 17 and 5.  His name is given as Powys in the enumerator’s sheet:

Name  Relation  Condition  Sex  Age Birth Year  Occupation  Where Born

POWIS, George Head M 58 1813 Oxfordshire
POWIS, Ann A Wife F 48 1823 Sussex
POWIS, Florence C E Daughter F 17 1854 Middlesex
POWIS, Letitia A Daughter F 5 1866    Middlesex
MALLINSON, Martha Servant F 30 1841 Surrey

RG number: RG10 Piece: 718 Folio: 54 Page: 7    

Registration District: Wandsworth Sub District: Streatham
EnumerationDistrict: 16  Ecclesiastical Parish:

Civil Parish: Tooting Graveney Municipal Borough:
Address: New Road Lilford Villa, Tooting Graveney
County: London, Surrey
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Aug, 2012: A second treasure chest from Peter Hodge, this time GHNTP’s son George’s baptism and showing that George had an elder brother Thomas Evans, born on 5th Aug 1844.  The 1851 census entry for Thomas was included.  So I’ve added him in.

Their marriage:

groom's name: George Powys
bride's name: Mary Ann Comley
marriage date: 26 Jan 1833
marriage place: Saint Mark,Kennington,London,England
indexing project (batch) number: M01557-1
system origin: England-ODM
source film number: 254601, 254602
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Their marriage:

Surname   First name(s)      District   Vol  Page
Marriages Mar 1853   (>99%)
FLORANCE Anne Amelia Kensington 1a 21
POWYS George Henry Norman Toovey    Kensington  1a  21
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