John Black Sheriff Substitute of Stornaway
Just out of curiosity, I had a quick look for this John Black.
He died in Stornoway in 1887, aged 59. In the 1881 census he and his sisters Katherine Inglis and Isobel Elizabeth, all unmarried, all born in Kirkcaldy, Fife were living together in Stornoway. They were three of the nine children of Roger Black and Rachel Law.
Roger Black was born in Kinglassie, Fife, and was a lawyer, and Rachel was born in Kirkcaldy. Roger Black, mother's maiden surname Inglis, died in Kirkcaldy in 1857, aged 60. Rachel Law or Black died in Edinburgh in 1872, aged 70. Their son, John's brother Roger, also became a lawyer, and was Procurator Fiscal in Kirkcaldy.
There are several obituaries for John Black in the Ross-shire and Fife local newspapers, from which he seems to have been the usual sort of exemplary chap. He was buried in the family grave in Kirkcaldy. I have no idea why his will turns up in the NZ probate records; it was Confirmed in Dingwall Sheriff Court (which is where I'd expect) on 25 August 1887 and Sealed in England on 9 September 1887.
(In Scots Law there is no such thing as Probate; the corresponding process is Confirmation. A will Confirmed in Scotland can be Sealed in another jurisdictions, and Probate granted elsewhere can be Sealed in Scotland, which saves having to go through the complete rigmarole in both or all jurisdictions.)