http://www.london-gazette.co.uk/issues/20822/pages/454/page.pdf - he may have been back by 1848 when he is listed as "of Brading" (previously of Cherbourg) in bankruptcy proceedings.
http://www.london-gazette.co.uk/issues/20826/pages/588 - and was put in the gaol of Winchester.
Manche records:
http://recherche.archives.manche.frIn the indexes for Cherbourg, recorded as "Prieur"
birth of William Henry, son of George + Philadelphia, 5 xbre (December) 1833
The original record registers him as the son of George Prior, carpenter, aged 37, and Philadelphia Nabbs, aged 37, his wife. The child given the names "William Henry", and the entry witnessed by "Jean Edouard" (signs "John Edward"), aged 49, a cooper, and William Hellier, 27, a sailor (unrelated to the infant: they are probably friends or coworkers of George ).
There is also a birth in Cherbourg for Esther Victoire Besnier, 8 8bre (October) 1827. Her parents are given as Jean Michel Besnier, carpenter (navy carpenter?), aged 31, and Genevieve Victoire Racine, his wife, aged 29, with Baptiste Besnier, shipwright, aged 29, cousin of the infant, and Julien Besnier, shipwright, aged 63, uncle of the infant.
her parents' marriage is recorded 17 Jan 1826, and she had siblings:
An unnamed child, d. 21 September 1826
Caroline Victorine, 13 May 1830 (married 1851 to Charles Antoine Renaudin)
Louis Victor, 8 October 1832 (died 9 November 1832)
Virginie and Alexander, 26 September 1833 (both died 29th October)
Eugenie Ernestine, 27 May 1835 (died 28 Jan 1836)
Albertine Alexandrine, 7 May 1837 (married 1855 to Francois Ernest Averton, died 1859)
Amand Isidor, 31 Mar 1840 (died 3 April 1840)
Josephine Marie, 21 July 1842 (died 2 Mar 1843)
Genevieve d. 26 Mar 1857
Jean Michel d. 25 Feb 1869
Jean' Michel's nephew, Edouard Laine, was a witness at his death but otherwise no relatives are listed.
I can't find a marriage between Esther Victoire Besnier and George Prior/Prieur, though, at least not in Cherbourg or on English/Welsh records in freebmd. It's possible it took place in some location near Cherbourg.
As far as I can see, their eldest child is William Henry, born in 1848 (Hampshire), married a Mary Fleming and later (like the others in this family) appears in Michigan - his spouse, Mary and his first child, Bessie/Elizabeth, are born Newfoundland according to the 1900 census. However, he is not christened until 1851 (familysearch.org) in Bembridge, around the time his brother James is born (James is christened early the next year).
Possibly there was some conflict due to the fact that the Besnier's were Catholic (
http://le50enlignebis.free.fr/spip.php?rubrique1323 shows both of the sisters were married at the church of de Voeu in Cherbourg), and the Prior family appear to be Anglican.
A birth certificate of one of the children born in England may help; if you can confirm Esther's parents' names, birthdate, middle name, etc, from other records then it won't matter so much if you can't track the marriage down.