If you have drawn a blank on him, Graimes is relatively unusual name, so try searching for possible Brighton born siblings on the censuses. Sarah Emily (b 1856) John (b 1860) Richard Berry (b 1861) Fanny (b 1862) Eliza Fanny (B 1864) Walter Abraham (b 1864)
I have found a William Graimes in Hove, but born 1868 not 1858. So I have to ask, especially as you have not told us the census you found your William on, are you sure you havent made an error of 10 when calculating his birth year by any chance? (There have been occasions when we've all done that)
Furthermore, could it have been him that married a widow called Mercy Funnel in 1899 in the Steyning district. Steyning also covers Hove by the way.
I did find a William H Grainer (General Dealer aged 44) and Mercy Grainer in Hamsey near Lewes in 1901. With them were their Brighton born children Ada (b 1887) and Albert (b 1896) but no Flora.
There were also two Graimes ladies on the 1911 Lewes census (a Lewes born Mercy Hannah aged 52 & Flora Frances Graimes aged 17) but Mercy was the head of household and no William was with them? Are both those combinations yours and do we presume William dead by then?
As the daughter Flora was 17 in 1911, and FreeBMD gives us no one called Flora or Florence Graimes, could it be that the Graimes marriage was a second marriage for Mercy, and the daughter was from her first?
There was a Mercy Turner who married a George Funnel in Brighton in 1881
Then a Flora Funnel born in Brighton in 1893
and a couple of George Funnells dying in Brighton in 1894 & 1895.
Trying to dovetail the above into your family history is very difficult until we get some more constructive answers, so the onus is on you to provide a few more details, including identifying the census where you got your info from and any other dates and places that might be helpful.
Have you the family on the 1891 census for example, and if so, can we have the details?
Roy G