Humph! Which colonists? The ones in N America or the rest of the erstwhile Empire? As it happens we all spell it the same way but I chortle at the inference that Americans have somehow expunged their colonial origins.

Welcome! Great name for one who is obviously not a philistine! Stick around, and may we all chortle in our glee.

So, Jo aka jmh [arched eyebrow emoticon], and any other fellow philologists out there: have we established there is indeed a "once-only 'ou' " rule among y'all in the UK & in the former colonies who still embrace the current Monarch's English?