> not include an overly emotive actor...

mmm, interesting - the OED2 gives this, from which I suppose a back-formation is only a hint away, but...

slang.


To act in a ‘hammy’ manner, to over-act. Freq. const. up. Hence "hammed-up ppl. a.; "hamming vbl. n. and ppl. a.

otoh, it's worth quoting a couple of the other hams which have also been mentioned here before, I think...
n2:
local.

A plot of pasture ground; in some places esp. meadow-land; in others spec. an enclosed plot, a close. Found in OE., and still in local use in the south; in some places surviving only as the name of a particular piece of ground.

and n3: The OE. hám home, which, in composition, has been shortened to ham, as in Hampstead, Hampton (:—Hámtún), Oakham, Lewisham, etc., and, in this form, is sometimes used by historical writers in the sense ‘town, village, or manor’ of the Old English period.