Extend the passcode lock timeout on iPhone 4S and iOS 5 connected to exchange
It appears I was slightly half wrong! The above mentioned post is correct and I managed to find the specified directory:


/var/mobile/library/configurationProfiles/PublicInfo


but only with iFile (not iPhoneBrowser). So I edited the files mentioned: "change maxGracePeriod and maxInactivity to 14400 (it's in seconds, not in minutes) in the files EffectiveUserSettings.plist and Truth.plist." and after a re-spring "4 hours" appeared as an option! Also I can now see that directory in iPhoneBrowser (may have been a fault?)

Hope this helps someone else!