I did find a newspaper article (1903) referring to a William Iddenden having 22 children in Herne Bay, which would be the correct location.
It is possible that he could have been married before, but I just don't know.
Is this the article?
William Iddenden whose progeny has
numbered twenty two applied to the County Justices at Canterbury for a vaccination exemption certificate in respect of his daughter,
Mary Alice born July 9th this year.
Reasons for applying lost three children, one at four, another seven, and the third at eight and that he had a conscientious objection to vaccination.
He had married twice;
by his first wife he
had fifteen children and the
second seven.
The magistrates contrary to the usual custom asked no questions, but granted the application almost immediately - the applicant was stated to be a Herne Bay man.
Canterbury Journal, Kentish Times and Farmers' Gazette dated
17 October 1903IDDENDEN, MAY ALICE
mmn BUNDOCK1903 S Quarter in BLEAN Volume 02A Page 999
Edit to add
Looking at the children’s names from 1891/1901 census
GRO indexes have these birth entries same mmn
Isabella Florence birth registered as Bundock (mmn blank) 1880
Not found a birth entry for Thomas from 1901 census or Rose A from 1891c
There is birth Canterbury 1887 Rose Ann Iddenden mmn Ovenden
1883 William James (mmn Bundock)
1885 Percy (mmn Bundock)
1890 Violet (mmn Bundock)
1892 Daisy (mmn Bundock)
1895 John Alfred (mmn Bundock)
1897 Stephen Walter (mmn Bundock)
1898 Jesse (mmn Bundock)
1899 Lily (mmn Bundock)
1901 Mary Ann Susan (mmn Bundock)
1903 May Alice (mmn Bundock)
1905 Ethel Ada (GRO index Ida Ethel mmn Bundock)
