Thanks for that Link New Judge.
As for "(what amounts to) Communism",
well frequent users - and particularly on this Forum - of this clichéd, massive paint brush term, "Communism", are not able to define it in their own words, never mind the ENORMOUS difference between "Communism " and socialism /Socialism, so a refining of what the RMT means by "4.(b) to work for the supersession of the capitalist system by a socialistic order of society; " is moot.
RMT OBJECTIVES AND CONSTITUTION OF THE UNION
'part 4.(h) to settle disputes between its members and employers, regulate the relations between those parties by the collective withholding of labour or otherwise, and to provide funds for the relief of members during trade disputes connected with their employment subject to these Rules;'
and '4.(k) to provide funds for legal assistance, strike and provident benefits as provided by these Rules;'
might interest DTCwordfan.