At his marriage to Mary he was ‘William Henry Fry’.

Neville Sarony has found a baptism record that might well be for this William, but it gives a birth date that is perhaps six years before the birth year from the ages he recorded at all the censuses.

The baptism record on the IrishGenealogy web-site si:

Area -             DUBLIN (COI) , Parish/Church/Congregation - ST. MARK
Baptism of         WILLIAM HENRY FRY of 4 WENTWORTH PLACE on 29 November 1848
Name               WILLIAM HENRY FRY
Date of Birth      27 July 1848
Address            4 WENTWORTH PLACE
Father             WILLIAM HENRY FRY
Mother             SOPHIA FRY
Father Occupation  DENTIST
About the record:
  Book Number  Page  Entry Number  Record_Identifier  Image Filename
  N/R          N/R   N/R           DU-CI-BA-118746    d-30-2-1-226

A scan of the register page can also be downloaded and from this some of the above details are unclear:

Address:     4 Wentwo... Place
Date of birth: 27 July 184?, possibly 1847  (But this does not squarer with aged 25 in 1873)

There is also a baptism in 1851 at St Peter’s of Geraldine Clara Fry with the same parents but at 20 Wentworth place instead of No 4.
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Then this c. 1848 birth must be compared with the census entries when he had moved to England:

Census  Age   Deduced birth year
------  ---   ------------------
1881     28   1853
1891     39   1852
1901     47   1854
1911     56   1855

These ages were inconsistent and he was obviously a little casual in the information he presented.  But did he really lop 4 to 8 years off his age?  If so, why?  

It is possible that the baptism was of an elder brother who died and that this William Henry was indeed born around 1853-4.

Sept 2020, TFPL: I have found his marriage register page for his marriage on 29th Nov 1873 and in this he said he was then aged 25, giving a birth year oc 1848, or possibly the end of 1847.  This ties up well with the birth certificate and I would surmise that he had not by then got to massaging his personal information to make him more appealing to customers; so I am accepting that baptism and birth date as kosher.
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Living places in the censuses:

1871: possibly the Wm Fry born in Ireland in 1854, a ship’s painter and living in Govan, Lanarks, Scotland.

1881: He and his family were in 13 Westbourne Terrace, Chiswick, Mx was:

  William, Head, 28, Portrait painter, b. Ireland
  Mary, Wife, 25, b. United States
  Maud, dau., 3, b. London
  Sophia, dau., 1, b. London

  (Mabel and William S absent)

1891: Family in Long Ditton, Kingston, Surrey with

  William, Head, 39, Portrait painter, b. Ireland
  Mary, Wife, 35, b. New York
  Mabel, dau., 16, b. Bedford
  William S, s,, 14, b. Bedford
  Sophia, dau., 10, b. London
  Ernest, s., 9, b. London
  May, dau. 4, b. London

  (Maud absent.)

1901: Family at 50 Beaconsfield Rd, Twickenham, Mx with:

  William, Head, 47, Artist (painter), b. Ireland
  Mary, Wife, 42, b. New York, USA
  Mabel, dau., 25, b. Bedford
  Ernest, s., 19, b. Shepherd’s Bush, Mx
  May, dau. 14, b. Surrey, Tolworth
  Leslie, s., 4, b. Surrey, Tolworth

  (Maud, William S, Sophia absent)

1911: Family at 43 Palewell Park, East Sheen, SW:

  Mary had had 7 children, of whom 6 were living (Maud deceased)

  William Rawstorne Frye, 56, Artist painter, b. Dublin, Ireland
  Mary, 52, b. N York US America
  William Sarone(?), 34, gun maker, b. Bedford
  Rag(?), wife of Wm S, 25, b. Belford, Northumberland
  Leslie, son of Wm S, 2½, b. Leeds, Yorks
  Ernest, s., 26, gun maker, b. Shepherds Bush, London
  Leslie, s. 14, at school, b. Surbiton, Surrey

  (Sophia, Mabel and May were sharing a house in East London)
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In 1913, he was on the Parliamentary Electoral Roll at 43 Palewell Park, Mortlake parish as “Frye, William Rawsthorne“.  Similarly in 1921.  1913 was the last electoral roll he was in on FindMyPast.

Mary would have been excluded as women could not then vote on parliamentary elections
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(Eileen Powys-Lybbe thought they had 5 children, but in fact it was 7.)
________________________________________

One of these could be his death:

Surname First name(s) Age District Vol  Page
Deaths Mar 1926   (>99%)
FRY William H 72 Kingston 2a 639   
Deaths Mar 1929   (>99%)
Fry William H 73 Marylebone 1a 1155

As could this index entry

First name(s) WILLIAM R
Last name FRYE
Gender Male
Birth day -
Birth month -
Birth year 1849
Age 86
Death quarter 2
Death year 1935
District SURREY NORTH EASTERN
County Surrey
Volume 2A
Page 142
Country England
Record set England & Wales deaths 1837-2007
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Their marriage index:

First name(s) WILLIAM HENRY
Last name FRY
Marriage quarter 4
Marriage year 1873
Registration month -
MarriageFinder™ WILLIAM HENRY FRY married
MARY SARONY
District SCARBOROUGH
District number -
County Yorkshire
Country England
Volume 9D
Page 684
Record set England & Wales marriages 1837-2008
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The marriage from FamilySearch:

Name William Henry Fry
Birth Date 1852
Age 21
Spouse's Name Mary Sarony
Spouse's Birth Date 1854
Spouse's Age 19
Event Date 20 Nov 1873
Event Place York, England
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Sept 2020, TFPL: Their marriage register entry is foun d!  It includes:

Location:    The parish church of St Martin, Scarborough, Yorks
Cert No:     89
Date:        Nov 29 1873
                        His                         Hers
Name:           William Henry Fry            Mary Sarony
Age:            25                           19
Condition:      Bachelor                     Spinster
Job:            Artist                       -
Residence:      8 Martins Terrace            Sarony Square
Father’s name:  late William Henry Fry       Napoleon Sarony
Father’s job:   Dentis                       Photographer

Celebrant       J Moore Lister, Assistant Curate
Witnesses       O Sarony, Ce(?) Curtip

The witness O Sarony was the brother of Mary’s father Napoleon.
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