Cheers Guys.
Got my knocking noise sorted today after following your advice.
Its been with the car for the last 18 months - now gone - nice one.
The garage were really helpful as well - they believed me and had a look!
The following Topics detail the problem in more detail:
http://forum.cliosport.net/display_topic_threads.asp?ForumID=2&TopicID=15307http://forum.cliosport.net/display_topic_threads.asp?ForumID=2&TopicID=15307
http://forum.cliosport.net/display_topic_threads.asp?ForumID=2&TopicID=22609http://forum.cliosport.net/display_topic_threads.asp?ForumID=2&TopicID=22609