The 1901 Portslade census may help, but unfortunately you failed to reveal your GG Grandfather's name.
If he was Alfred, he was one of the last in quite a large family.
Alfred's parents were John W Cook born 1849 Brighton & Elizabeth born 1858 Shoreham
His siblings were:
Thomas 1875, John W 1887, Emily 1889, Elizabeth 1892, Sarah A 1895, and Jane 1898
John senior only married Elizabeth in 1880 (Steyning district) so Thomas (as Tomas in 1881) may be the result of a previous marriage.
There are other children shown on the 1881 & 1891 censuses and in 1881 John of 9 North Street Portslade is recorded as a Brickmaker from the Cliftonville district of Brighton
Elizabeth would appear to have been the daughter of Charles Mustchin of Washington & Eliza. As for John Cook born Brighton c 1849, the most likely candidate is a John William Cook born to John & Sarah in Brighton in 1847, but you would need to have a copy of his marriage certificate to Elizabeth to be sure. John and his presumed parents can be found at various locations in the Steyning district on the 1851 - 1871 cenuses.
It should also be noted that in that particular era, that area was heavy with brickyards.
Roy G