Missing from 3 census's....

[harrison]

I am waiting for the birth certificate o my STEP grandfather for confirmation of his parents,but I know from his marriage certificate that his father was called William.I have found what looks like "our" William on the 1881/91/1901 census,& according to these 3 census's William White was born 1841/2 Epping,& his wife Elizabeth born abt 1852 Greenwich.But a search (by others)for William on the 51/61 & 71 has not come up with him,does anyone have ANY idea as to why this would be.He would have only been about 9 years old in 1851 & even if his parents had died/abandoned him or whatever he surely must be somewhere.   Joan.