ibm's defense in the antitrust case can be read as an source par excellence for the european and japanese computer market in the early 1970s.

in a nutshell, then, what's bad for IBM international these days is good for IBM's defense in the U.S. government's antitrust suit | w. david gardner, 'ibm's defense' datamation, march 1974

in court ibm attorneys talk about "the club", a term also used in some eu papers, missing an explanation, though. in general they are not very descriptive, if you don't know the time and its players.

the court, i know, said [thomas] barr [ibm's lead attorney], is aware of the 'cartel system' ... there is an organization known as The Club, to which Control Data belongs, to which International Computers of England, which is a company substantially owned by the British government, belongs, ...| same source as above

the unidata venture was another european attempt to combat ibm. (siemens, germany; philips, netherlands; cii, france); actually it was ill-fated, but maybe of use for ibm at the time.

another thing to consider is the shortage crisis of energy, that influenced development, not just in europe. one answer to conserve energy was the "three day week". advanced memory system (ams) in silicon valley did it:

we have four shifts, each working 12 hours a day for three days. the result has been encouraging as ams has thus obtained 20% more facility time without any increase in energy consumption. | to conserve energy, datamation, 1974

as the world well knows, current U.K. regulations give the office world normal lighting and heating just three days a week while they struggle through the rest of the time wearing warm underwear and huddling near windows or peering through the light of lamps run on camping gas. | u.k.'74, michael blee, datamation

if you were working with computers, you didn't have the hurdle to deal with camping gas, those companies have been granted "special position" by the government.