This is the first time I have seen this registrar since my searches that have look at all designs from January 1956 onwards.
The registrar is Marcella Jackson, Renato Rigliorini, Danieli Magi and Vasco Licci! The really interesting part is that their agent is Wilson, Gunn & Ellis. They were also used by Nieri.
I have not seen an image of this design yet, so I don’t know if there is a Nieri influence or not.