Her baptism transcription:

First name(s)           Eleanor
Last name               Powys
Birth year              1773
Birth date              13 Feb 1773
Baptism year            1773
Baptism date            16 Mar 1773
Father's first name(s)  Thomas
Mother's first name(s)  Eleanor
Parish                  St George, Hanover Square
County                  Middlesex
Country                 England
Page                    144
Archive                 City of Westminster Archives Centre
Record set              Westminster Baptisms

And the Baptism register actually read, from the page found, thanks, on Ancestry:

“Baptisms March 1773
“. . . .
“16 [day of March] Eleranor D. of Thomas Esqr. & Eleanor Powys.    13 Feb [birth]”
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LDS Vital records:
On 9 March 1814, in Clun Shropshire, a James Powys was christened, mother Elinor Powys, father not entered.  Might this be her?  There are two other candidates for this Elinor.
On 25 Jan 1823 also in Clun, Shropshire, an Elizabeth Powys was born to John Powys and Betsy.  There is also an Elizabeth who appears in the 1881 census in Rickmansworth, born in Shropshire.
On 10 November 1844, again in Clun Shropshire, a Mary Powys was born to John Powys and Jane.  I think these three births must be relations, somehow.
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Oswald Barron, in his VCH genealogy volume for Northants, calls here Helena.  As yet I have found no records to support this.
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Their children are, from a search for baptisms from 1801 to 1821 on Ancestry with the surname of Stopford and parents’ forenames of Richard and Eleanor:
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Her burial

First name(s)  Eleanor
Last name      Stopford
Gender         Female
Event year     1854
Burial year    1854
Burial date    16 Dec 1854
Burial place   Barton-Seagrave, Northampton, England
Place          Barton-Seagrave
County         Northamptonshire
Country        England
Record set     England Deaths & Burials 1538-1991
Category       Birth, Marriage, Death & Parish Records
Subcategory    Parish Burials

Their marriage abstract:

First name(s)           RICHARD BRUCE
Last name               STOPFORD
Title                   Hon
Marriage year           1800
Marriage day            10
Marriage month          Nov
Marriage place          LILFORD
Parish                  Barton Seagrave
Occupation              Reverend
Spouse's first name(s)  Eleanor
Spouse's last name      Powys
Spouse's title          Hon
Spouse's parish         Lilford
Event Type              Marriage
By Banns or licence     Licence
County                  Northamptonshire
Country                 England
Record set              Northamptonshire Marriages
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The transcript by me from the Marriage (and Banns) register of St Peter, Lilford, (it was Lilford on the front page) Northants:

“Banns of Marriage                           10 November 1800
“
“The Honble. and Revd. Richard Bruce Stopford of the Parish of Barton Seagrave in this County and the Honble. Eleanor Powys of the Parish of Lilford were Married in this Church by Licence this tenth Day of November in the Year On Thousand eight Hundred by my W.V.Robinson Clerk
“This Marriage was solemnized between us:  R.B.Stopford, Eleanor Powys
“In the presence of:  Courtown, Lilford.”
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