Hi Steve
I haven't found William, or his wife, in the census returns yet and I have a sneaking suspicion that they may have lived in Dunkirk for a while (their daughter Eliza moved there about 1840 - she married a local innkeeper in October 1840). William's wife, Mary Ann, is thought to have died in Ostend sometime before 1867.
Do you have the marriage record of the daughter Eliza of Dunkirk and the death record of William's wife Mary Ann of Ostende? The marriage record could contain the place where her parents lived at that time and the occupation of her father.
I have just found the marriage entry at Dunkerque (Online Archives of the Archives
départementales du Nord) Dunkerque mariages 1830-1845, page 507 on the left side
http://www.archivesdepartementales.lenord.fr/?id=etat_civilWilliam Fowler, officier de la marine anglaise, demeurant à Cork en Irlande
Marie Anne Claringbold, décédée à Ostende
It also says that Eliza already had a child named André Thomas Fowler, born in Ostende, Flandern 17.12.1830.
Birth record of Andreas Thomas Fowler, Oostende 17.12.1830
https://www.oostende.be/file_uploads/17512.pdfDeath record of a person named Fowler 19.02.1830
I only saw it in the index but couldn't find the record.
There is a remark on the index which I can't decipher.
https://www.oostende.be/file_uploads/17711.pdfI also searched for a death with surname Claringbold and found the following record:
20.03.1834 Marianna Clarington, born in Kent, England, wife of Henricus Fowler,
lieutenant of the "Engelsche See-Macht" what means the English Marine.
https://www.oostende.be/file_uploads/17715.pdfRegards
Svenja