iPhone 5 not pushing emails

I have a new iPhone 5 3 days old. I had my iPhone 4 backed up to iCloud and restored the 5 to the last backup. My 5 won't push email alerts through even though in settings/mail contact/ calendars the fetch new data is set every 15 mins and advanced is all set to push. If I manually click on the mail icon it downloads the latest messages but it won't do it automatically. The 4 used to do it fine.

Please help as I desperately need my mail to notify me as soon as a new email comes through (for work)

Cheers