Brandy Margarine?

Just for a chuckle.
We past this while toddling the streets of Carlisle. My mind shot back to the "Hists of Mistory", when "Times waz 'ard".
We had a visitor to the house, I may have misremembered who so I'll not name him, coz it's so long ago it's as much from hearsay as memory.
Apparently Mam asked the visitor if he'd like any Rum Butter only to hear this small voice muttering "Brandy Margerine, Brandy Margerine".

Point of order Mr. Chairman.
I think, but a brief hunt cannot substantiate it, that I may have heard recently on a food programme that
either
It was no longer legal to call/sell the substance as Margarine
or
The name had dropped from popularity and you'd not be able to buy anything actually labelled "Margarine"?

Anybody put me right?