I have read with interest - and some amusement - Sean Matgamna's history of the "Irish debate" in IS and elsewhere on the left in the period from the late 1950s to (presumably) the early 1970s. I will not comment on the series as a whole until it is completed. However I would like to comment on the most recent in the series dealing with the Irish Workers' Group and - more specifically - its predecessor, the Irish Workers Union.
Sean's account is broadly correct. But it is ludicrous to assert that the IWU enjoyed sympathy from from Irish Catholic clergy or some "unidentified" part of the Irish political establishment. There is not a fragment of evidence for this and Matgamna offers none. To the extent that either of these social groups were remotely aware of the IWU, they would have regarded it as more extreme and dangerous than the Connolly Association which - although wedded to the Stalinist view of history - enjoyed close links with respectable even middle of the road forces in the Labour party - including in Parliament.
It is true that the original 1959 IWU constitution - written as he says by the anarcho-syndicalist, Michael Callinan - banned from membership both fascists and "communists". However this was opposed by some of us from the start (notably Mike Quilty a building worker member of the Socialist Review group, myself (who was to join the SR at about that time) and the late Dick Walsh who co-edited the Irish Worker with me. The ban on "communists" was dropped a year later. Although a marginal publication, the Irish Worker did briefly enjoy some readership among then (then considerable) Irish building worker labour force in London at that time. Indeed these links were part of the reason why Pat O'Donovan and - briefly - Brian Behan were involved.
The IWU was indeed politically eclectic. It included both some ex Clann na Poblochta militants and some who were in or around the Irish National Union in London (a dissident republican faction sympathetic to Saor Uluadh/Liam Kelly et al.) This may explain why Gerry Lawless and others from the Christle faction gravitated to the IWU prior to its demise and who then attracted some militants - including Liam Daltun (who as SM rightly says was politically impressive) - to what morphed later into the Irish Workers Group.
I trust at some time in his series Sean Matgamna will spell out clearly what concrete lessons he draws from the whole period for socialists in relation to what developed subsequently in the north of Ireland.