TFPL, Sep 2004:

Shropshire: Shrewsbury - St. Mary Parish Registers, Lichfield Diocese
Burials, Wedd. & Christnings,
  Burials, Wedd. & Christnings,
   1788.
County: Shropshire
Country: England
12 Apr 1788 John, s. of the Rev. Edw. Powys & Mary, (born 06 Jun 1787 ), bap.
_________________________________________________________

In 1799 a John Powys and his brother Henry were admitted to Shrewsbury School; The age is right so I think it has to be this John and his brother.  See Shrewsbury School Register, pub 1898, pp. 2.3.

In 1830 a Yorks, Leeds & West Riding Directory had some pages on a List of Bankers in Lond which included a lisyt of branches of the Bank of England in and which the Swansea Branch had John Parry Wilkins, Esq . A . ; John Powys, S . A. as the Agent and Sub-Agent respectively.  Again, almost certainly this was him and I conclude that he was a banker as well as a merchant.  The fact that the Agent was his brother-in-law is supremely irrelevant.
_________________

His burial (Glamorgan FHS) - his age ties in exactly with his known birth date:

Forenames: JOHN
Surname: POWYS
Abode: SWANSEA
Day Month: 22 JUL
Year: 1834
Age: 47
Parish: Oystermouth All Saints
_________________

And see his Will, part 2 for his brother Thomas, for two more sons.

His will was written on 1st November in two parts.

Part 1 left all his assets except for £400 to his dear wife Helen.

Part 2 concerns the £400 left in trust to his brother to provide for his further children with Margaret Johnson:

“My Dear Tom In my last will dated the first day of November 1833 I have left the sum of four hundred pounds our of my effects to you in Trust to appropriate as I will now direct  Prior to my very happy ... and lawful marriage with Helen Tobin Hughes I formed an unfortunate connection with a Servant who lived with Harriet and myself at Eveston / the fruits of which were the birth of two Boys now living  the mother’s name is Margaret Johnson the oldest Boy Robert Powys born in 1827 the youngest Henry Johnson born 1829 all of whom are now living at No 24 Firth Buildings First Street Liverpool  During my life I hope to provide for them by an annual allowance but at my death I wish you to apprpriate the interest of the aforesaid sum of £400 to their support and education & if not sufficient you will have the goodness in your discretion to lay out as much of the principal as you may judge right to that purpose and if any eligible opportunity occurs of putting either or both of the children out to an apprenticeship or any other situation to be hereafter of Service to them to make use of the money in such way always bearing in mind the poor Mother who I wish should  during her life have the means of living comfortably.  At the death if the two children should survive the principal and interest or so much of it as may be left I withs to be divided between them & in case they should die & any of the money remain unpaid in your hands the same may be given to my dear wife & children  Trusting my dear Tom you will not think this last request from a brother too troublesome believe me to be your very affectionate Brother John Powys -- Bank of England Branch Swansea 1st November 1833.”

Two gents of the area, John Jenkins of Swansea and Thomas Attwood of the same were sworn as witnesses to the fact that the will was in the hand of John Powys of Swansea, Glamorganshire and of the parish of Oystermouth also in Glamorganshire, all on the 16th September 1834.

Helen Powys was then sworn in on 22 September 1834 in London as the sole Executrix to both parts of the will and to duly administer both parts of the will.
_________________

Harriet, above, was presumably his younger sister and who married John Parry de Winton, previously surnamed Wilkins) and had issue.
_________________

Their marriage bond for an intended marriage, from FamilySearch:

name: John Powys
event: Intended marriage
event date: 05 Jun 1829
event place: St. Philip, Liverpool, Lancashire, England
gender: Male
age: 21
spouse: Helen Tobin Hughes
spouse's age: 21
digital folder number: 4018644
________________

Transcription from an image of their marriage register:

Where: Parish of Liverpool at St Philip’s church, Lancs
Year: 1829
Cert NO: 337
Date: 6 Jun 1829

Details Groom Bride
------- ----- -----
Name John Popwys Helen Tobin Hughes
Status: Batchelor Spinster
Parish Swansea, South Wales Liverpool

Married by: Licence
Witnesses: Nick Hughes, Horatio(?) Belper(?) Hughes, Mary Ann Hughes.
Celebrant: Edward Powys, Rector of Bucknall
_______________

No marriage record found.  The inly information is that a bastardy case was tried in Norway after the birth of her son and that she asserted that the father was Mr Powys from England.
__________________