Hi JK:
Benjamin Alexander Hewitt married Mary Ann Heritage who was my gg grandfathers sister in 1843 in St. George Hanover Square London - his father is listed as Benj Alexander Hewitta as well. I lucked out on finding this information only as there was a Thomas Hewitt living with my Heritage's before Mary Ann married. In the 51 census brother Edwin is living with them.
This is the only sibling I found for my GG grandfather, and couldn't track them past the 51 census - there were a LOT of Hewitts in Marylebone/St Pancras.
He is listed as a Carpenter in the 41 census and Joiner in the 51
I have born c 1821 - could it be your line ?
Regards,
LTS