Assuming I've correctly managed to attach the image, it seems from the chart, IMHO, that E1 begins after the Cat 1 hold and that it is Link 1 up to that point. A and B2, on the other hand, are charted with the taxiway designation before their hold lines. I would therefore think that "checks below the line" would take place after crossing the Cat 1 hold onto E1 as there is no turning back at that point. Unless of course you're ordered to vacate via 16/34 in which case it wouldn't seem that much of a big deal to simply comply with the ATC instruction. You don't wait until you're lined up to go below the line on any plane that I've flown, none of which was an Airbus. Sort of no huge deal but enough cringe factor after hearing the exchange to know it wasn't good.
