Oh - sorry.
My point was in fact rather more tasteless than has been supposed. It's nothing to do with Welsh pronounciation
per se; it was referring to the fact that many of the American vistors to the Ebbw Vale Garden Festival pronounced "Cwm" as "Quim", blissfully unaware of its anatomical connotations. I used it in a poem and the comedian Victor Spinetti incorporated it into a stand-up routine. Here in the Valleys, we get our giggles where we can.