Hi Twiggy,
I've just found this thread. Better late than never.
I have no idea why the 1871 cnesus says James is John, but all else about the entry fits.
1881 James MacFAYDEN, the police sergeant, is a widower, aged 49, born Scotland, and living at 31 Edward St, Westgate, Newcastle.
His son Robert John is living with James' parents, Donald & Jessie (SINTON) McFADEN at Horsley Cottage, Rochester.
Son Peter I'd not found beyond 1871 until I found this thread.
James' 1st wife Elizabeth ATKINSON had died in 1875.
I believe James remarried in 1884 to Rachel GIBBINSON, and it looks like he died in 1891 qtr 1, aged 59.
1891 Rachel McFADEN is a widow with son Robert J, 18, clerk with her, and living at 31 Edward St.
I've looked at the 1901 census image referred to above, and I cannot turn it into Peter at all, it really does look like Telis, with a clear dot above the i.
However, the theory that this is Peter does look good, as I've certainly not found a death for him in England between my 1871 sighting and this 1901 one.
Corsenside is a place connected with my other SINTONs, and James' brother Peter was at Corsenside in 1851.
Regards
Lorna
http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=GET&db=lornapotential&id=I14886