I would like to know more about this label which comes from a dress with tabard, I think circa 1970s.
It's not a label I've ever come across (I'm in UK and was based in London until recently). If you want help dating the tabard, please post pics of the whole garment. A Companies House search shows a Robina fashion house in London that was incorporated in 1984 and dissolved in 2013. The brand may have existed before the company formation though. https://find-and-update.company-information.service.gov.uk/company/01828679 It looks like a family business with the surname Ziff, including Robina Ziff. A quick search suggests that Robina Ziff was connected with Escada in Bond Street, who once dressed a young Diana Spencer. http://www.ncweb.com/users/jem630/nettie.html
Thank you very much for this information that’s really interesting, something for me to look into further. I’ll post a picture of the dress and tabard later.