smallcompany - 3:48 pm on Mar 24, 2012 (gmt 0)

On the server configured in CGI mode, a change in PHP handler directive produced the desired result. The old was:
AddHandler application/x-httpd-php5 .html .htm

The new one is:
AddHandler application/x-httpd-php .html .htm

The support said this:
As the server is already using php5, it was making redundant calls that did not work.

So viva the support that resolved it in their first attempt!