Highly interesting in various ways, the "to-ing and fro-ing" concerning far-extended lines tapping the Arigna coal area -- all looks to have been something of a "late to one's own funeral" situation: project undertaken in a big way, just when the writing was clearly on the wall -- boom-time never happened for it, and it ended up short-lived.
A thing which I have seen discussed elsewhere, re the C & L and its coal traffic -- how "from start to finish", coal was always transferred from n/g to b/g wagons at Dromod and Belturbet, using the most primitive method possible -- gangs of men with shovels. There's mention in the linked-to material here, of railways' managements contemplating at times, mechanising the transfer process, at least at Dromod -- but such a thing was never put into effect. I being fond of the whole narrow gauge / wider gauge "transporter" thing; have mused on how transporter-type doings being brought in on the C & L, must at least have occasionally crossed managerial minds -- though of course it never happened.
A favourite Utopian rail fantasy of mine, involves the C & L's ending up as Ireland's last-and-greatest 3ft. gauge system to survive in a meaningful form -- with it in fact still resplendently in use, and doing a vital job, in spring / early summer 2019. It hangs on the Arigna coal mines (if I'm right, in boring real life no longer functioning at all) being a rather "bigger and better" coal source than they in fact were; and its having continued to be highly necessary to get the coal out and send it to various other places in Ireland. Some sixty years ago, it's decided to smooth out the precious mineral's transit, by introducing on the C & L, 3ft. gauge transporters of whatever kind ("proper" wagons with rails mounted, a la Leek & Manifold; or small trucks with s/g wagons fitted between, as at various places on the European continent; however it might be) with which to run broad-gauge wagons between the mines, and the "off-the-narrow-on-to-the-broad" (and vice versa) facilities installed at Dromod.
Assorted other changes on the system, around this time. The County Donegal Joint system closes down at the end of 1959: CIE buys from it various useful gear, including a few of the steam locos to help out the C & L's weary and worn varied loco fleet. With the broad gauge at Belturbet abandoned; C & L's Ballinamore -- Belturbet section correspondingly abandoned circa 1960. A curve installed west of Ballinamore, to allow coal trains direct running between Dromod and the mines. Abandonment of the West Clare section early in 1961, allows transfer to the C & L of WC's diesel railcars and diesel locos (plus any useful rolling stock). This enables, fairly speedily, dieselisation of ordinary everyday C & L services -- passenger service Ballinamore -- Arigna withdrawn early 1960s -- ex-WC railcars (helped out by ex-Donegal ditto?) maintain the continued Dromod -- Ballinamore pass. service. The diesel locos handle the coal traffic, plus whatever general freight might for a while, continue.
Above situation seen continuing for forty years or so. Come the turn of the 20th / 21st centuries: with coal traffic still flourishing and seen likely to continue so for decades to come; and passenger Dromod -- Balinamore still prospering -- new diesel locos for the former, and new railmotors for the latter, ordered "from whoever / wherever".
Meanwhile and from early on, the C & L and Ballinamore and its works, become the centre of 3ft. gauge preservation for all Ireland -- CIE and later Iarnrod Eireann looking benignly on, and aiding, this to the max. A goodly number of steam locos already on the C & L -- ex-original C & L / Cork, Blackrock & Passage / Tralee & Dingle / Donegal -- are kept to preserve. Any other surviving 3ft. gauge locos / railmotors / stock, whatever ownership, are welcome to spend time on and be availed of facilities of, the C & L. From the early-ish 1960s till today, regular seasonal tourist-and-gricer steam passenger trains are run Dromod -- Ballinamore -- Arigna; any additional steam specials are welcomed and facilitated. (Steam passenger stock kept, from the first, in plenty, for such use; and as above, all assistance given re preserving of anyone's same.) Exchange stuff done, for fun and interest, with the Isle of Man's steam railway. Some at least of the ex-West Clare railcars and diesel locos, after withdrawal from everyday service, are preserved for special-occasion use; likewise ex-Donegal railcars.
A delight for railway enthusiasts; plus, a big "tourist draw" generally, brought in for an in the main rather overlooked part of Ireland -- everybody wins ! If only...