Having rasied this issue with HTC UK, their response was:
Dear Steve Loveridge,
Thank you for your reply to my email regarding the cermaic casing chipping off your HTC One S for which you have got a replacement.
No official statement has been made by HTC on this issue, but please keep your eye on the official HTC.com web page and linked Twitter feeds and Facebook pages for any official HTC statements.
I hope you are enjoying your new phone nad have no further issues.
Althouigh I have seen a statement from HTC made a statement via a number of websites (see earlier post), but it does not appear to be formally recognized by HTC UK.