I have looked at the Banns of marriage for East Hanningfield from 1824 to 1837 and there's nothing for a John Juniper. So, this means that either John and Mary Ann married somewhere else or it was by licence. I haven't got marriages before 1837.
As you are probably aware, John Juniper died in 1847 and his burial is registered as being on 24/8/1847 Age 36 in East Hanningfield. Mary Ann is a widow in 1851 with the children.
I had a quick look at the East Hanningfield baptisms too for John And Mary Ann's children and spotted the following;
1/3/1834 Elizabeth Ann
5/3/1837 Jane Eliza
12/5/1839 Ann
6/11/1842 Harriet Matilda
7/9/1845 John
There is also an entry on 21/5/1849 for a Mary Ann, Illegitimate daughter of Mary Ann Juniper, widow.
I hope this helps.
