The marriage certificate of Henry and Katherine, which you can get direct from the GRO (www.gro.gov.uk) for £9.25 using the following reference:

Jan-Feb-Mar 1849

Registration district:
Amersham

Volume Number:
6

Page Number:
369

will show his father's name and occupation. This, combined, if you are lucky with one or more witnesses from his side, should help you move backwards.