And more importantly (and probably somewhat more binding), the terms & conditions link that your "important information" link brings you to also has £300 fee on the last page.
https://secure.cmax.americanexpress....Conditions.pdf
however the terms and conditions page that you are offered when you click "apply now" has £450
The interesting thing is if I go to my personal referral page, and click "apply now", its a different summary of the pre-requisites (age, min income, uk resident, £300 fee), but the T&C link appears to bring you to the £450 document.