Can't believe I'm replying to a 12-year-old post, but I've only just spotted it.
Zachariah Belcher was the brother of my 4g-grandmother Jane Belcher. My interpretation of the records is that he was born in Birmingham in 1765 and moved to Sheffield in the 1790s with his wife Martha.
My 2g-grandfather Charles James Belcher left London for New York in 1855. He was a bookkeeper and Thomas, William & Charles would have been his father's cousins so I've always wondered if he went there to be the bookkeeper for their company. Does anyone know if employee records are available for the company anywhere?