How now brown cow?

Does everybody know this phrase?

And what is its origin?

The most common view is that it was used in elocution lessons. Usually it is traced to a newspaper article in America in 1926.
But it became a slang phrase said to mean “What’s up? Or What’s next?”

But it is complicated by the claim that a brown cow was the name given to a barrel of ale in 18th. Century Scotland and the phrase was the question of whether everyone was ready for another round.

It also seems that it was the title of a song in a London theatre musical a kind of precursor to The Rain in Spain.
And it was the title of a book for children published in 1994.

Of course the full phrase is “ How now brown cow grazing in the green green grass.” And I know that in elocution lessons this was designed to teach we Yorkshire men how to pronounce grass! They tried to persuade me it should rhyme with farce. I told him that was a farce. I said he was being a silly ass and he could pronounced that however he wished. and that if he was right it would be spelt grarce. Proud to be a northener.

And all this nonsense arises from looking out of my window this morning at the field across the road where all the other 18 cows were black.