This is Viennese (style) coffee – it's the fig – and I can imagine it being mighty popular in the 70s. After, was there ever a biscuit more exotic than the fig roll? Not since Garibaldi patented his process for embedding dried fruit into layers of cardboard, had such a marvellous, cosmopolitan confection entered into our teatime retinue.
In Vienna, they sprinkle some kind of fig dandruff on top of normal coffee (generally topped with cream beforehand), before demanding an implausible number of euros in return.
Anyways, Sainsbury's still sell Viennese-style coffee replete with figgy flavouring if you are after a fix. Alternatively, dunk fig rolls in normal coffee. As per the usual dunking methodology, at some point a substantial part of fig roll will defect to your beverage.
