John Guilford married Jane Clarkson in 1846, Liverpool. At this time he was a book keeper, father Samuel, Labourer. A witness was James Gilbertson.
John and Jane had 3 children: James Clarkson Guildford (presumably named after Jane's father, James), Mary Guildford and Samuel Guildford. I am guessing that they broke with the tradition of naming after the paternal grandfather first either because they lived near James (jane was born in Liverpool) or because James had died and was being honoured by the couple. Given that the 2 grandfathers' names appear amongst the children's, it would be reasonable to assume that Mary was a grandmother's name.
John died just before the 1851 census was taken, but in 1841 there is one good match, John Guildford born Scotland aged 25 (so 25-29), here he is a labourer, but is round the corner from James Gilbertson of Scotland, a book keeper.
In 1851 there is an Edward Guildford of Scotland, aged 31, lodging with the Price family in Everton, Liverpool. He looks like he may be a brother.
In 1861 Edward Guildford is in Hill St, Everton with housekeeper, Caroline [Garner?], aged 48, married, born Birmingham
in 1871 Edward Guildford is at 11 Thorncliffe Rd, Everton with wife E [S?] Caroline Guildford aged 63 born Birmingham (almost certainly the housekeeper of 1861, but no marriage can be found).
Edward Gilford died in Liverpool aged 57 in 1876
Now to Samuel/Mary
One thing to bear in mind here is that John's son, Samuel Clarkson Guildford was lodging in Cumberland in 1861....
1861 Arthuret, Longtown, Carlisle, Cumberland
James M Coward. 28. Bobbin Turner. Staveley, Westmorland
Agnes Coward, wife. 26. Scotland
Samuel Gilford. 75. marr. Boarder. Railway Lab. Scotland
Mary Gilford. 67. marr. Boarder. Railway Lab's wife. Scotland
John Hall. 2. Boarder. Wetheral, Cumberland
Samuel Gillford died Longtown Jun Q 1861
An Agnes Guildford married in Carlisle Mar Q 1869 to Telesforo Perez or William Armstrong
1871 Bothergate, Carlisle, Cumberland
Mary Guildford. 82. Widow. Scotland
Agnes Guildford. 33. Dau. Unm. Charwoman. Scotland
Whether the Agnes who married is the same woman, in which case she had quickly reverted back to her maiden name, I don't know.... but this is a very rare name in Cumberland.
As you can see, I' working on some supposition with the extended family, but I feel quite confident that these are connected to my John, especially now I have supporting evidence of John being Scottish.
I cannot locate Samuel or Mary before 1861, or Agnes before 1871. Nor can I find Edward before the Liverpool census of 1851.... I have been through all the possible spelling variations, and searched on just forenames, in English and Scottish returns.