Returning after quite a few years away and saw your thread. Stuart is on Facebook and should be reachable, as Arkle suggests. His Kelson Collection site is both good visual and historic documentation of the collection, and the notes page has some patterns which are not in The Salmon Fly or Tips.
As Stuart notes, Kelson was a character who lived large and enjoyed salmon fishing and fly dressing. There is still much material in his writings to be looked at by us, more than a century later. There are a handful of dressings which were published in other sources, and there are discrepancies in some of the dressings that were published in different sources.
The Inky Boy debacle was but one of several disputes which played out in The Fishing Gazette, Land and Water, and private correspondence. Speaking of the vast amounts of dyed materials, have you heard of the standard colours? Prior to 1883, Kelson wanted a standard set of colours for dressing flies, so that when referenced by pattern or colour, any houses or dressers could provide flies that were "true to colour." Despite his drawn-out promises, he was never able to fully develop them and drive them through the industry. He feuded with James Noble, junior, who provided dyed seal's fur at Kelson's request for the 1883 Exhibition. He feuded with another dye house to whom he had gone to produce the colours for display at the Fly Fisher's Club. He exchanged barbs with R. B. Marston regarding the colours through and after 1896, the year of publication of The Salmon Fly. He bemoaned not having the colours, and lamented that he had wanted them before the colour plates were published in Land and Water, following the fly descriptions that were published in the Fishing Gazette and Land and Water. The colours in the Collection are likely the closest that we will get. (Fast forward to the 1980s, and there was a revived effort to establish the colours, which again did not succeed.)
Our art has an interesting history, of which Kelson is only one character. Always glad to discuss what I've researched with others.