EI-DVM,
I may be out-of-date here, but I always understood the the 2 'intermediate' approach control positions for EGLL were manned by 2 ATCOs per frequency.....These were, or maybe still are, the positions that control the holding-stacks and the a/c leaving them. BNN/LAM and OCK/BIG. The 'final director', responsible for the final turn on and approach spacing, was usually single-manned.
Another possibility is that the 2 voices could have come from an ATCO trainee, and his/her instructor/mentor?
If anyone who's current on EGLL approach could tell us how it works at the present time, it would be interesting to catch up.
Also, many of the U.K. area frequencies have 2 ATCOs on them, called Radar/Co-ordinator, or Tactical/Planner. It is usually the Radar/Tactical's voice that you hear, but the Co-ordinaor/Planner, occasionally transmits messages.
Last edited by ZOOKER; 25th Aug 2017 at 15:31.