My family back in the US say I definitely sound more "English" nowadays, (after 20 months), in my cadence, enunciation, emphasis on words or syllables, and choice of words or phrases. To them, it is most pronounced and distinctive.
I hardly feel it myself, but sometimes when I say things to myself like "bloody hell!" I have to stop and giggle, because time was that those phrases just didn't trip swimmingly off my tongue.
New people I meet here usually think I'm Canadian (rather than American, late of Texas, born and raised in Georgia, educated in Indiana). Not sure why, but they're always surprised when I correct them. No idea what my long-time Brit friends think.
Oh, and my dry wit has definitely become drier. Funnily enough, my Brit friends think that's the Texan in me, rather than any influence of theirs. (Hmmm, I doubt I've become more Texan living in London.)