Thanks for your efforts. I got hallingham from the actual census image itself and have just tried the "magnifier " on it again to see it it could be wrongly transcribed, but no.
I had also discovered the hallingbury,s and they are close to herts but when i followed the Google trail to an online genealogy page it looked liked another typo ( like mine above - hallinham )
There seem to be no other references at all in Google to hallingham.
One possible lead is that in 1851, Francis's younger sister ( Frances ) is living with the family and is recorded on the census sheet as being born in Essex, Sheering. There is a sheering too a couple of miles south of the Hallingbury's