I seem to be having issues with ecryptfs and restoring /home.

I currently have a seperate /home partition and would have created a user with an encrypted /home, I have extracted my passphrase with
Code:
ecyptfs-unwrap-passphrase .ecryptfs/wrapped_passphrase
and stored this separately as stored_passphrase.

I have then backed up the users .Private/ folder.

When I delete the user and recreate with encrypted home again and login as user and add the original passphrase with
Code:
ecrypt-add-passphrase stored_passphrase,
then logout and restore the backup of .Private/ when I login I cannot access the restored files.

This appears fundamental to me as although I backup my full /home partition currently if I needed to reinstall following a data loss I would not be able to access my encrypted /home folders.

Am I doing something wrong. Note I do not want to access the files from a live CD, I want to be able to access /home following a reinstallation of the OS.