I think Sandra misread the year of birth. There were actually two Robert BUCKs born 1867 - 1869
Robert BUCK Jun 1868 Depwade
Robert BUCK Sept 1868 Loddon
Both appear on the 1871 census with their respective parents: Henry & Mary Ann give their son's place of birth as Long Stratton (covered by Depwade district), while George & Harriet's son was born at Ellingham (covered by Loddon district).
I checked out the many public family trees you mentioned and not one even mentions Robert BUCK's marriage, although they do show his wife as Florence Jane SANDS.
Robert & Florence were married Jun 1890 Mutford v.4a p.1409
If you order a copy of their marriage certificate it will provide you with the name and occupation of Robert's father and clear up the mystery. It's quicker, and cheaper, to order online direct from the GRO at:http://www.gro.gov.uk/gro/content/