Annette: Yes, all confusing isn't it! When this started out it confused us as well.
We have positively discounted the Elizabeth SARAH Humphries baptised at St Nicholas Brighton daughter of George & Elizabeth as that family appear not to have had any later connections to Brighton. So put them to one side for the time being.
Elizabeth SOPHIA Humphries; Her father was a publican John Terry Humphries in Lambeth London. Her mother Sarah (ms Walesby) was his second wife.
Details from birth certificate of John Laing HUMPHRIES;
Registration District, BRIGHTON, The Palace, County of Sussex. No 31. 11th April 1857, 24 Oriental Place. Sex, Boy. Mother's Name, Elizabeth Sarah Humphries. Signature, description and residence of informant, John Laing, occupier, 24 Oriental Place, Brighton. When Registered, Twentyfirst April 1857. George Smith, Registrar.
24 Oriental Place was a good class lodging house often used by John Laing's brother the Reverend David Laing when staying or preaching in Brighton. He was responsible for building Holy Trinity church at Haverstock Hill in west London.
We presume that John Laing did not know Elizabeth's second name or was confused at the time he registered the birth. He later married a woman whose name was Sarah. (his second wife) Or maybe the name Sarah was used to confuse other people including us! Perhaps the registrar was hard of hearing, who knows? Yes, people did spell phonetically.