The article is about the Ennis labourers in Ireland in the early 1930's. The bit about the Shrewsbury trials is an aside about how the author came to know more about the events, hence not really the place to discuss the evolution of Ricky Tomlinson's politics.
I don't know anyone on the left who denies that as a young man Tomlinson was involved with the far right, including Tomlinson himself who in interviews has spoken thoughtfully about how it was a result of poverty and lack of education and how he later became a socialist.
"One would have felt that the left could have favoured a less unsavoury person to have championed."? It was the bosses who chose to victimise Tomlinson and his co-defendants. Maybe you think the left should pick and choose which victimised workers to defend according to whether they have racist, sexist or homophobic ideas?
What the bosses objected to about the picketing - and you too it seems by your uncritical quoting of the appeal judge - was that it was effective: large numbers of pickets moving between sites shutting them down and where necessary the equipment too. Scabs were "put in fear"? Good, that was the idea!