Her baptism transcript, by me:

“                       Page 223
“ BAPTISMS solemnized in the parish of St Pancras in the County of Middx in the Year 1815
“. . . .
“When baptiozed:           May s
“No                        1780
“Child’s name:             Margaret Ann
“Parent forenames:         Donald and Jean
“Parent’s surname:         Maclean
“Abone                     Brunswick Square
“Profession:               Gentleman
Birth date:                March 15 1815
“Celebrant:                Robert Mayne, Rector of Limpsfield, Surrey
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The followin baptisms have been found on Ancestry

Year   Name                      Parish
1834   Peter Leversage           Eastington
1837   Mary Leversage            Cainscross
1840   Edward Howard Leversage   Cainscross

and that seems to have been that!

But the censuses may show different children living with Margaret Ann.
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In 1841 the above three children were the only members of the family at Ebley, Randwick, Stroud, Gloucestershire:

First name(s)  Last name  Sex  Age  Birth year  Birth place
Peter      Leversage  Male    35  1806  Gloucestershire
Margaret   Leversage  Female  25  1816  -
Peter      Leversage  Male     7  1834  Gloucestershire
Mary       Leversage  Female   3  1838  Gloucestershire
Edward     Leversage  Male 10m  1831  Gloucestershire
Elizabeth  Page       Female  30  1811  Gloucestershire
Hester     Sealy      Female  25  1816  Gloucestershire
Mary       Winn       Female  15  1826  Gloucestershire

REF:       1841 ref: HO107, piece 370, book 14, folio 47, p. 5
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In 1881 her surname was written as Seversage (I would guess this was a copying error by the enumerator) and another son had been born in 1855 and Margaret, plus Mary plus this son they were at 18, Aldridge Rd Villas, Paddington, Kensington, London:

First name(s)  Last name  Relationship  Marital status  Sex  Age  Birth year  Occupation  Birth place
Margaret Ann   Seversage  Head      Widow   Female  66  1815  Annuitant                   London, Middlesex
Mary           Seversage  Daughter  Single  Female  43  1838  -                           Gloucester, Glos
Cecil Deworth  Seversage  Son       Single  Male    25  1856  Commercial Clerk Insurance  Clifton, Somerset
Sarah          Rowley     Servant   Single  Female  23  1858  Cook                        Tasley, Shropshire
Martha         Coudren    Servant   Single  Female  24  1857  Housemaid                   Paddington, Middlesex

Ref:
Archive reference RG11
Piece number 12
Folio 78
Page 10
Combined:          1881 ref: RG13, piece 12, folio 78, p. 10
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In 1891, Mary was away from home but Cecil had joined his mother with his wife (for a visit or were they living there? all at the same address of Villas, Aldridge Road, Paddington, London:

First name(s)  Last name  Relationship  Marital status  Sex  Age  Birth year  Occupation  Birth place
Margaret A  Leversage  Head      Widow     Female  76  1815  Living On Own Means  London, Middlesex
Cecil       Leversage  Son       Married   Male    35  1856  Sugar Broker Agent   Clifton, Somerset
Ellen       Leversage  Daughter  Married   Female  36  1855  -                    London, Middlesex
Margaret    Sullwan    Servant   Single    Female  31  1860  Cook                 West Drayton, Middlesex
Mary        Sullwan    Servant  Single     Female  25  1866  Housemaid            West Drayton, Middlesex

Ref:
Archive reference  RG12
Piece number       11
Folio              33
Page               60
Combined:          1891 ref: RG12, piece 11, folio 33, p. 60
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In 1901 Margaret has reached a mighty 86 and had her daughter and her widowed second son with her at the same residence of 18, Aldridge Road Villas, Paddington, London:

First name(s)  Last name  Relationship  Marital status  Sex  Age  Birth year  Occupation  Birth place
Margaret   Leversage  Head            Widow    Female  86  1815  -         London, Middlesex
May        Leversage  Daughter        Single   Female  62  1839  -         Gloucestershire
Howard     Leversage  Son             Widower  Male    60  1841  Manager   Gloucestershire
Dora       Leversage  Grand Daughter  Single   Female  21  1880  -         London, Middlesex
Elizabeth  Salusbury  Servant         Single   Female  30  1871  -         Devon
Rose       Cooper     Servant         Single   Female  28  1873  -         Surrey

Ref:
Archive reference RG13
Piece number 10
Folio 34
Page 60
Combined          1901 ref: RG13, piece 10, folio 34, p. 60
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Her death index:

First name(s)  Margaret A
Last name      Leversage
Gender         Female
Birth year     1816
Age            90
Death quarter  1
Death year     1906
District       Paddington
County         London
Volume         1A
Page           9
Country        England
Record set     England & Wales Deaths 1837-2007
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Her probate index:

LEVERSAGE Margaret Ann of 18 Aldridge-road-villas Westbourne Park Middlesex widow died 20 January 1906  Probate London 2 February to Cecil de Worthe Leversage esquire  Effects £1408 11s.
219
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DRom an image of the parish register on Ancestry, transcript by me:

[                   Kings Stanley  >  1833                  ]

“MARRIAGES solemnised in the Parish of Kings Stanley in the County of
“Gloucester in the Year 1833
“. . . .
“Peter Leversage of the Parish of Eastington in this County & Diocese Esqr Widower
“and Margaret Ann Maclean of this Parish Spinster
“were married in this Church by Licence with Consent of Parents this Twentieth Day of
“June in the Year One thousand eight hundred and thirty three
“     By me Jeremiah Smith Curate
“This Marriage was solemnised between us [signed] Peter Leversage  Margaret Ann MacLean
“In the presence of [signed] D Maclean  Charles Kelson  Mast??? Holme  James Walters Kelson
                             F Lycatt(?)  S I Maclean  E F ??????  D M Princes(?)  Kate McLean
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