Some contacts in iCloud not syncing to IOS6

I am attempting to sync contacts on an iPad, iPhone 5 and PC running Outlook 2010 under Windows 7. All the Outlook 2010 Contacts have sync'd to iCloud Contacts and MOST (95%) of the iCloud Contacts have sync'd to both the iPad and iPhone. I suspect there must be some coding on the Outlook 2010 Contact record which is preventing an iCloud-IOS6 sync but I cannot see anything! None of the contacts which have not sync'd are marked as 'Private' in Outllook 2010.

Any suggestions would be great! Thanks. Ian