There are a number of charities with the leters SOS as part of their name so at this time it’s not clear which of the charities was being represented.

I had thought it was the following charity SOS Children’s Villages but a post by Loving Lena Zavaroni suggests that it must be another charity.

Performers

Australian EntertainerRolf Harris
Scottish SingerLena Zavaroni
English VentriloquistRay Allan
Ventriloquist's DummyLord Charles
English ActorClive Dunn
ImpressionistKaren Kay
MagicianJohn Wade