OK, I found it!!

My Mum, bless her, rang an old friend, and got the recipe for me.

Merrily's Broken Biscuit Cake

250g broken plain biscuits
100g copha
4 tablespoons of golden syrup
2 tablespoons of cocoa

Melt the copha in a pan, and add the golden syrup and cocoa. Melt and combine all together.
Add the broken biscuits and combine really well.
Press into a slab tin
Score into fingers & refrigerate