I'm curious what makes you think otherwise?
The lower class, of course, largely were servants.
The industrial revolution opened up other avenues for employment.
Edit: see, for example, http://www.bl.uk/victorian-britain/articles/the-victorian-mi...
"A middle class woman was entirely dependent on a supply of domestic servants, ranging from the untrained ‘slavey’ to a staff of several highly trained specialists."
I'm curious what makes you think otherwise?