twinkle, I think the crisps with the blue salt bags were 'Smith's Crisps', they gave you the choice of salt or dry, the modern day versions are full of chemical additives, a wonder we are still alive.
The square tins in which the crisps were packed and distributed, became a useful household container for various other items (so I'm told), I believe my grandmother kept all the boot polishes in hers, happy days 'eh, Oh for the return of such days, doodle bugs, incendiary bombs, barrage balloons, such JOY !!!.