I've extended the stereo image of expresso love by using a simple L+R L-R, increase L-R gain and do the opposite method and it doesn't really look a full mono signal. Nevertheless, it doesn't look a wide stereo like the FM broadcast.
Attached mp3 sample. You can compare to
and you will see it's not mono.
According to wiki the first NICAM broadcast was The Proms in July 1986:
https://en.wikipedia.org/wiki/NICAM
Entirely possible the show was made in stereo for futureproofing but unlikely it was broadcast in stereo IMO.
Broadcasted in mono or stereo?
According to the video credits they used the Rolling stones mobile so I guess they have the sound in good stereo
The concert was a multitrack record by Rolling Stones mobile (same as Alchemy). Then different mixes were designed for different uses. They can made a stereo mix for FM stations, and a mono mix for TV broadcast (or an alternative stereo mix for TV broadcast).
The question is about that this official YouTube release is true mono or very discrete stereo mix. FM stereo mixes are very wide.
Maybe the multitracks are still alive today, those are the key to make a new stereo, 5.1 or ATMOS mix. And the original video tapes (not this digitalized TV broadcast). An example is "Delicate Sound Of Thunder" by Pink Floyd. They used all the original material to make a new video restoration and re-edition and audio remix. We can hope for a Wembley '85 BD in Full HD or 4K if this material is available.
