I presume you have searched the census records for your missing Percy Constantine Nicholls Tim. He is not with his family in 1881 at 14 Sandringham Road, listed are father William, mother Ann and siblings William S, Sidney V, Henry J, plus a servant Elizabeth Henderson. The 1891 census shows an additional daughter Caroline E born 1868, plus more siblings Elsie W and Anne S, following this family through the various census records is interesting and I thought that maybe Percy would pop up somewhere but no joy, sorry. I cannot find a death for him, he must be somewhere. Good luck with your search.