Backing vocals on the Mad, Bad and Dangerous tour

After listening to the Frankfurt recording, I've noticed that on some songs (Closer To You, Sister Blue,...) you can hear a voice that sounds similar to Suzy O'List/ Gill O'Donovan. However, they were only on the 1988 tour with the former appearing at the Marquee 1992 gigs. Did they decide to give someone a pitch shifter for the main tour(excluding Geneva)? It's not Spike's vocoder I'm hearing

Peter Noone did most of the backing vocals, with a bit of Clayton Moss. Spike could have been triggering recordings of female vocals, though

Probably Peter Noone then. You can hear the aforementioned voice shout "Clap your hands" during the breakdown of Sister Blue.

If it's spontaneous, then it's definitely a fella. You can trust me on this, I was there.

Thanks for the clarification.