he does not appear to be in 1881 census (? away at school)
presume parents are John Frederick Gill (s/o Deemster Fred Gill - who was bro of Wm W Gill - plenty of info on these on Manxnotebook + in new Manx worthies) - JF's wife Eliz Agnew Mitchell - in 1881 at (Rose Cottage) 2 The Green Castletown
however don't seem to have any record of him - I presume you have tried manx museum library@mnh.gov.im ?