According to the London Gazette, the bancrupcy proceedings against Herman started in 1811. He was variously described as a fish merchant from Hackney Road, Middlesex & of Lower Thames Street in the City of London as well as Rotherhithe. Historical Directories might give you some more clues.
His son, Ernest George Frederick was also listed in the gazette for bancrupcy in 1835. He's described as of Carpenter St, Mount St, Grosvenor Sq, Upper Ranelagh St, Belgrave Sq, Middlesex. A coal merchant, dealer & Chapman.
It would appear that Ernest George died Q1 1850, Uxbridge RD.
The National Archives showed a divorce petition for a Johann Henrich Sievers in 1864. There might be a connection there?
Also a death reg. on FreeBMD for Herman Ernest Sievers Q4 1845, Chelsea RD...perhaps another connection?
1841 census shows EGF (listed as Geo) at Doddington Grove, St. Mary Newington, Sry. Age 35...? merchant, not born Sry with wife Arabella (25) also not born Sry
jane