Graham,
You are correct (as always!) 
Mark 2 Powerlink cable is the one to use for any application where you are NOT directly connecting Beolab speakers to one end of the cable (ie. if you are using MCL2P, Beolink Passive in Powerlink mode, etc). This is because these items require both pin 1 (Powerlink On) and pin 4 (Mute) to be connected, whereas the audio circuits in the majority of non-display Beolab speakers trigger from pin 4.
The exceptions to the above are the older Beolab speakers with displays and Beolab 5, both of which use pins 1 and 4 for triggering.
To clarify my recent discussion with KingOfSnake (as referred to above), this was in general terms about trigger functions within Powerlink cables, so I was speaking in terms of Beolab speaker triggering, rather than for use with Beolink Passive/MCL2P. Hence, I had mentioned to him that most Beolab speakers trigger from pin 4, with pin 1 only being required for Beolab 5 and speakers with built-in displays.
Hope this helps!
Best regards,
Steve (off outside to enjoy the sunshine!) 
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