text: It's been more than 8 years but if I remember correctly this is based on personal survey of the area where I marked building numbers according to the markings on the buildings at the time.
  
  Even though 8a isn't officially recognized it shouldn't be ignored based on that, per the ground truth policy (https://wiki.openstreetmap.org/wiki/Ground_truth). Since it's been a long time, it might warrant another trip to verify it's indeed there or gone.