I am slightly puzzled by your message, because I can't find you on the tree I have, and I can't see how you can be a nephew of Fr Bernard Leeming SJ if you are also the son of John Birch Leeming.That may simply be my own ignorance, of course!
According to my records, which I got from our cousin Michael (John Michael Andrew Wilson Leeming) who as the senior male holds the family pedigree, John Birch Leeming (my mother's first cousin) had three children by his wife Gwendolyn Winfred Taylor: Christopher John (b 19.8.46), Peter Harland (21.9.47 - 30.12.67) and Stephen Metters (b 5.5.50). In that case, where do you fit in?Curiously, the tree I had on my pc showed 'unnamed spouse', with no further detail at all.Did your father marry again?Do tell me more.
Bernard, I think, must be the same relation to you as to me, as you and I share the same great grandfather Henry Heatley Leeming.Bernard was my 2nd cousin twice removed, being the son of Henry Heatley's cousin Harold Francis.
Incidentally, our common ancestor is another John Fishwick Leeming (1833-1907), the brother of Bernard's grandfather Francis Theodosius.I got into trouble with (your half-brother?) Chris for referring to him as a 'pompous ass'.He thought I was talking about 'Gramps', your grandfather, the aviator and author!If you would like to know more about J F Leeming senior, and why I gave him that epithet, do let me know your email address.