Her baptism transcript:

First name(s)           Mary Elizabeth
Last name               Welbank
Birth year              1812
Birth date              26 Mar 1812
Baptism year            1813
Baptism date            01 Apr 1813
Father's first name(s)  George
Mother's first name(s)  Anne
Parish                  St James, Piccadilly
County                  Middlesex
Country                 England
Page                    37
Archive                 City of Westminster Archives Centre
Record set              Westminster Baptisms

The text of the register entry is:

Church:                St James Westminster, Middlesex
Borh:                  12 April 1812
Baptised               1 Apr 1813
Forenames:             Mary Elizabeth
Parents forenames:     George & Anne
Surname                Welbank
Abode:                 St James’s Place
Occupation:            Broker
Celebrant:             J Glen
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It looks like her mother died at her, ME’s, birth; then her father died in 1821 when she was 9; I wonder who looked after her from then?  Her mother’s sister, Elizabeth?  Elizabeth survived until 1868.
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Her death certificate, Epsom district no 478 (or possibly 418) says she died on the 15th Feb 1885 at Horton Manor, Epsom, Surrey, aged 72, of "Ascites Anasarca", informed by W Sampson Trotter her son who was present at the death and lived at Horton Manor, Epsom and registered on the 17th February 1885 by James Andrews, registrar.
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Her burial at Epsom & Ewell Cemetery:

Trotter     Mary Elizabeth
wife of     William Trotter
Age:        72
Residence:  Horton Manor, Epsom
Burial:     18 Febuary 1885
Grave:      A34A
Register:   1364
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TFPL, November 2020: I have long wondered who looked after her after both her parents died.  I had speculated that it was the Trotters.  The discovery of the Welbank pedigree in the College of Arms opens up the possibility that it could have been either the family of her father’s brother Robert and his wife Sarah or the family of her her father’s sister Harriet and her husband William Sampson.

But Robert was a sea Captain in the far east and his wife might have been abroad with him.

On the other hand William Sampson was a merchant and was found in the 1841 census in Eaton square with Harriet, so he had a few bob to live there.  I had been unable to find his death date as there are nearly a thousand William Sampson deaths within thirty years on either side of 1840, they married in 1803.  In 1851 Harriet was staying with her brother Robert and was a widow, so William died before 1851.  This census information then led to finding his will of 1850 which mentions his Eaton Square property and Robert Welbank and Harriet.  This then led to his death record of 1850.

And then I reviewed the names of Mary Elizabeth’s children.  The first son was Sampson Henry Brown but he died soon; the first daughter was Harriet Amelia Brown and the second son, after the death of the first was William Sampson Brown.  I conclude firmly that Mary Elizabeth gave them these names in honour of the couple who took her in when she and her brother George had been orphaned.  QED?

Definitely QED from the will of Harriet Sampson, Mary Elizabeth’s paternal aunt, who effectively made Mary Elizabeth her heir and devoted mush of her estate to Mary Elizabeth’s children.

March 2021, TFPL: I have finally located her marriage record and yes, as expected, Wm Sampson and H Sampson are the first signatories on the list of witnesses.
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Her probate index:

Trotter, Mary Elizabeth
(482) Personal Estate £20

The will of Mary Elizabeth Trotter (Wifeof William Trotter) late of Horton Manor Epsom in the
County of Surrey who died 15 February 1885 at Horton Manor was proved at the Principal Registry by the Reverend Henry Eden Trotter of Ardington Vicarage near Wantage in the County of Berks Clerk and Ernest Balfour Trotter  of 5 Maddox-street Regent-Street in the County of
Middlesex Esquire the Sons the Executors.  Probate being granted under certain Limitations.  Special Administration granted at the Principal Registry April 1885.
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TFPL, Nov 2020: With the discovery  of her father’s arms, granted in 1808 shortly before his marriage, she has become not only an ordinary heiress, the only surviving grandchild of her Trotter grandoarents. but also a heraldic heiress carrying her father’s arms and her mother’s Trotter arms, her mother having also been always a heralidc heiress in her issue.

I had been uneasy about the fact that in the Royal Licence of 1668 she had been said to carry the Trotter arms from her uncle when she was not even armigerous as, to the best of our knowledge, her father had no arms to make her into a heraldic heiress.  I had once asked the York herald about this and he gave the answer that the kings of arms could more or lass grant arms to whoever they wanted and in whatever manner they chose.  The heraldry game, then, had no rules.  But now the true facts are known, there is no problem with the inheritance of the old Trotter, and now the Welbank, not to mention also the Brown and the new impartible Brown-Trotter arms may be inherited by us P-Ls through our Trotter grandmother Lilian also an heraldic heiress in her issue through her father the heir in his issue to his elder brother the eldest surviving son of William and Mary Elizabeth Trotter.

Now for the pedigree to show this Trotter inheritance and then to redraw the P-L quarterings to include the Welbank arms and the P-L pedigree to show the inheritance of all the the quarters.  And then to get it all printed out, hopefully for the last modification in a fair while.
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From Saint James’s Chronicle of 26 August 1834:

MARRIED
Aug 21, at St Mary’s, Bryanston-square, William, eldest son of the late George Brown, Esq., of Russell-square, to Mary Elizabeth, daughter of the late George Welbank, Esq., of St James’s-place.
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March 2021, TFPL: After a massive search taking hours on Ancestry I did manage to actually find this original record and have transcribed it:

“MARRIAGES solemnized in St Mary’s Church, in the Parish of St Mary-Le_Bone, in the County of Middlesex in the Year One Thousand Eight Hundred and Thirty-Four
“. . . .
“William Brown of the Parish of St James Westminster Esquire  Bachelor
“and Mary Elizabeth Welbank of the District-Rectory of
“St Mary in the Parish of St Marylebone,  Spinster
“were married in this Church by Licence
“this twenty-first Day of August in the Year one thousand eight hundred and thirty-four.
”By me  Henry Brown M.A. P Curate of Tandridge
“:This marriage was solemnised between us [signed] Willm Brown  Mary Elizabeth Welbank
“In the Presence of Wm.Sampson  Sarah Welbank  H Sampson  Robert Welbank  G Brown(?)
No: 114”
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It is worth noting that the first witnesses were William and Harriet, née Welbank, Sampson as they had taken Mary Elizabeth into their care when she was totally orphaned in 1820.  This I had previously deduced from William Sampson’s will but this additional information confirms my previous thought.
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March 2021, TFPL: Their marriage licence, transcribed by me:

2/6d
LONON DIOCESE
15 August 1834

APPEARED PERSONALLY William Brown of the Parish of St James Westminster in the County of Middlesex Esquire aged twenty one years & upwards Bachelor

and Prayed a Licence for the Solemnization of Matrimony in the District Church of St Mary in the parish of St Mary lebone in the same County

between him and Mary Elizabeth Welbank of the District of St Mary in the said Parish of St Mary le bone of the age of Twenty one years & upwards and a Spinster

and made Oath that He believeth that there is no Impediment of Kindred or Alliance, or any other lawful Cause, nor any Suit, commenced in any Ecclesiastical Court to bar or hinder the Proceeding of the said Matrimony, according to the tenor of such Licence.  And He further made Oath, that the said Mary Elizabeth Welbank hath had her usual place of Abode within the said District of St Mary in the said parish of St Mary lebone for the space of Fifteen days past  [signed] Willm Brown

Sworn before me [signed] William Robinson surr
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