This really is what I know as 'hedgehog' slice. I used crushed shortbread biscuits as I cannot get graham crackers in Australia and sultanas instead of raisins and butter as I prefer not to cook sweets with margarine. The result was yummy and for our tastes was sweet enough to for go the icing.
I've lived in New Zealand for 21 years, and I haven't the slightest clue what a "graham cracker" is!
Lliving in nz for 2 years i find it strange that a recipe calls for "marg" not butter.