What is Stewie's accent? [Family Guy]

On family guy, the character Stewie talks with an odd accent.
It’s not British, I believe.
Is that a synthetic accent?
My apologies if this is for Cafe Society. I couldn’t decide, since accents are real and Stewie is fictional.

It is an exaggerated British accent based on Rex Harrison.

I think its meant to be Seth MacFarlane’s take on a British accent (specifically some kind of Professor Moriarty style victorian villian).

Cite

Reminded me of this: http://www.youtube.com/watch?v=Wxm2E7i2lLE