To bite ones thumb

I've used the expression "thumbing your nose at someone" to mean a kind of contempt. When I looked in Phrase Finder for confirmation it didn't seem to be included.
Any info anyone?
Thanks, Rosieann

Certainly in the part of London I grew up in in the 1930s and 40s, 'thumbing your nose' was very popular with kids as a form of defiance against almost anyone else - other kids, grown ups (you hoped you weren't indentified while you were running away, which is what you always did if adults were involved!). I don't know its origin but I guess pretty old, possibly centuries. It was almost never used by adults and was regarded as childlike.

I'm under a similar impression regarding the above, and believe it to be a now out-moded and almost certainly entirely British childish insulting gesture. To effect it, simply hold your right hand side-on to your face, with fingers extended upwards, place your thumb against the tip of your nose, and then, facing your target, waggle your fingers. God alone knows how it came about.

I wonder if it's at all related to biting ones thumb as an insult. I found it in Romeo and Juliet

GREGORY
I will frown as I pass by, and let them take it as they list. [41]

SAMPSON
Nay, as they dare. I will bite my thumb at them, which is disgrace to them if they bear it.

ABRAM
Do you bite your thumb at us, sir?

SAMPSON
I do bite my thumb, sir.

ABRAM
Do you bite your thumb at us, sir?

SAMPSON [Aside to Gregory]
Is the law of our side if I say ay?

GREGORY [Aside t