WOW!
I've not had that for yonks.
I remeber "stork margerine was the best for the job. Not sure of the quantities though, it was very simple, just hand mixing in the bowl with flour. apple, apple & black current or just black current from natures larder, should be just coming into season now.
Maybe a little drizlle of honey on top?
Blackberries would be my preference over blackcurrants for a crumble but my favourite fruit for that pudding is rhubarb.
Tinned peaches go well in a crumble, too.