Okay Greg,
I have Arnold Kellett's excellent book on my lap.
Of relevance to your quest. It has a whole chapter on the life story of Thomas Clark 1775-1859 who wrote Cranbrook. Although first published in 1805 it was probably written a couple of years earlier and named after the village of Cranbrook in Kent.

'Precisely who the originators of the song were, and where they came from, is still confused and controversial...... Much is still mysterious, and has defeated some of the most dedicated investigators. In 1958 a member of the University Song Book Committee stated that in 1922 the committee had tried, and failed, to track down the origin of the song, and that experts like Frank Kidson and Professor F W Moorman had also been baffled by it.
But we can at least clear the ground by looking at the most widely accepted tradition that OIM came into being as a result of an incident that took place during a ramble and picnic on the moor. It is further generally believed that the ramblers were all on a chapel choir outing, from one of the towns in the industrial West Riding.'

P68 'Cranbrook was also familiar as a Christmas carol when used, particularly in Yorkshire, for 'WSW'. Indeed according to Dr Pat Morris and Dr Ian Russell, it was the most commonly used tune for this carol until 'Winchester Old' was popularised by Hymns Ancient and Modern from 1861 onwards.'
'OIM was for many years--perhaps for more than half a century--a matter of oral tradition. The nearest approach to anything historical is in the earliest published version of the song--both words and music--which appeared in 1916.
This rarely seen version, entitled 'On Ilkla Moor baht 'at'--a dialect song from the West Riding, set to 'Cranbrook', was published in September 1916 as sheet music by J Wood and Sons of Huddersfield jointly with Novello and Co, London. It was collected by Charles H Dennis, a schools inspector who lived at Fartown, Huddersfield. He was something of a composer himself, having written in 1914 the anthem 'Huddersfield: A Song of Home' which was sung in local schools.......Dennis was particularly fond of OIM, both words and music, and went round collecting versions 'from those who have sung them----in some cases for very many years.'

Kellett then goes on to translate, explain, and dissect the earliest published version in great detail.

He then prints a version which appeared words only in a 1915 newspaper The Yorkshire Weekly Post, suppied by Mr A S Robinson of Redcar, words as we sang them in Leeds a good many years ago.

He then goes on to look at counter claims for its origin as being on 'Baildon Moor' . There is a claim that a John Ellis of Bradford wrote it! There are also claims on dialectic terms that it came from the Halifax area. Dennis apparently conjectures a date of origin around 1856.

In my own collection of Yorkshire sheet music and 78s I have 4 items of relevance, the original 1916 sheet music as mentioned above and an undated copy derived from this, published by Banks of County Arcade, Leeds.
The 78s are Broadcast Twelve Series 5128-B as sung by The Sheffield Orpheus Choir. (Traditional)and Rex 78 8145-B sung by Lesley Sarony and vocal quartette, again designated traditional.