Groups 1-3 have always been on the right for me on that gate. Generally a dozen or so in front of me as well. Not sure about behind but the group 4-5 queue stretches back a bit.
Just don't do a Ryanair and turn up at T-13 to find you've been offloaded.....
At least BA do final name calls over the tv system so you know you can waltz up last at that point
The terminal is too narrow to do any real queuing properly. Look at when FR are boarding from say Gate 52. The queue generally stretches back in front of Gate 51 and people tend to just join the first queue they see (even if their flight is at Gate 56). Badly placed pillars and that new coffee shop don't help with queues and people trying to get past.
Same with the area around gates 44-48. Get a couple of FR flights and a AF/KLM or Flybe there at the same time and it's bedlam trying to figure out where your queue is, especially at the bottleneck corridor leading from gate 49.
A move to T2 would be fun. Can take up to 20mins to walk to some gates at present....