The Prince of Wales always wears a cutaway collar with ties. As has been said earlier, his ties are invariably striped the original British way, and are often the ties of regiments of which he is Colonel in Chief, or other service ties. It is, of course, seriously bad form for anyone who has not served to wear a regimental, corps or service tie to which they are not entitled, so we should not expect Ernest to pursue his quest to emulate the British too assiduosly.
Yes, I have heard that the British are quite upset by the improper use of regimental / university neckties, thus I have avoided their patterns to avoid any problems. Luckily, there are hundreds, if not thousands of non-organizational ties out there that are perfectly suitable and whose patters are for the most part are indiscernible to the general population. Jon.