Hello Langwell,
John MacKay 'Hereford' was an important figure in the land risings and cultural awakening in Gaelic Scotland in the 1870s and 1880s. If you check out the early editions of 'The Celtic Magazine' and the 'Transactions of the Gaelic Society of Inverness' you will see him regularly featured there. I think he is also known as John MacKay 'Swansea'. If it is the same man he was chieftain of the Gaelic Society of Inverness in the late 1870s and you will find at least one speech by him. The one I have found is in volume 8 of TGSI. Here is a link to a page where you can download volume 8 of TGSI:
http://www.smo.uhi.ac.uk/en/rannsachadh/leabharlann/seirbheisean-air-loidhne/irisean-leabharlann/He was also the key figure in founding the Rogart Educational Association to support education - including through the medium of Gaelic - in his native parish of Rogart in the very far north of Scotland.
In this regard, the following poem was made for him by John Stuart Blackie, poet, activist and scholar, who was described as 'the greatest living Scotsman' of his time:
TO JOHN MACKAY, ESQ., OF HEREFORD, THE FOUNDER OF THE ROGART SCHOOL
ASSOCIATION, SUTHERLAND.
Who love the Highlands ? not with murtherous guns,
Who scour the moor, and chase the flying deer ;
Who lure the speckled troutling from the mere,
And hook the strong-nosed salmon, where he runs
Cleaving the adverse flood. These love their sport ;
But thou, Mackay, dost love the stout-thewed men,
Whose sweatful toil redeemed the stony glen,
And filled wide Europe with the proud report
Of their high-daring deeds ; and thou didst stir
In fresh young hearts brave memory of their sires ;
And mothers hailed in thee God's minister,
To fan the slumbering flame of patriot fires.
Who loveth thus loves well, and, nobly wise,
Weds earth to heaven with worth that never dies.
JOHN STUART BLACKIE.
You will find the poem and a short speech by John MacKay in the 8th volume of the Celtic Magazine, which can be found in the same link as above.
MacKay also published work on the poetry of Rob 'Donn' MacKay, generally considered to be among the greatest of Gaelic poets. It would be interesting to know if John MacKay was related to Rob 'Donn'.
Best wishes on your research,
Iain MacKinnon
Good luck with your enquiries.