Here's the way I learned it:

My mother was a lady, the urge you would allow.
You may have a sister who needs protection now.
I came to this great city to find my brother dear.
You wouldn't dare insult me, sir, if brother Jack were here.

The youth sat there in silence, his head bowed down in shame.
"Excuse me miss, I meant no harm. Pray tell me, what's your name."
She told him and he cried "Alas! I know your brother true.
For we've been friends for many, many years, and he often speaks of you.
So come with me when I go there, and if you'll only wed,
I'll take you to hiim as my bride, for I've loved you since you said,

'My mother was a lady, the urge you would allow.
You may have a sister who needs protection now.
I came to this great city to find my brother dear.
You wouldn't dare insult me, sir, if brother Jack were here."

I always wondered if "the urge you would allow" wasn't right. Perhaps it should be "and yours I would allow."

I've been trying to remember another song my grandmother sang to me - there were three - "My Mother Was a Lady" "The Skinniest Man" and another one I can't remember.
J