Thanks Flanker,
Interestingly I did try the Lost Planet profile as discussed in this forum. I do take notice of what you guys recommend
However, the sky was just flickering constantly. So, I experimented and tried other profiles after downloading the latest CAP from AMD and randomly found that the Warhammer Space Marine profile worked perfectly. I was on max settings and getting 35+ FPS all the time with no stutters, flickers or anything.
The only problem I could find was that the lettering in Mission Builder was all "fuzzy" but still readable. Once the game was started it was fine. On leaving the game I disabled Crossfire in ATI Catalyst and went into my Windows Live Mail - the lettering in the menu sections was "fuzzy" but the email notes themselves were crystal clear? Will have to play around with display settings to sort that out.
For your interest I have attached the ATI Catalyst settings that I applied to the profile.