Problems with installation from ppa:ondrej

Problems with installation from ppa:ondrej

The server is running Lucid and I am trying to upgrade the PHP to 5.5 stable.
I followed the intructions on this question: http://goo.gl/aryB4m
root@32772-201711:~# add-apt-repository ppa:ondrej/php5
gpg: keyring `/tmp/tmpZCjHpD/secring.gpg' created
gpg: keyring `/tmp/tmpZCjHpD/pubring.gpg' created
gpg: requesting key E5267A6C from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpZCjHpD/trustdb.gpg: trustdb created
gpg: key E5267A6C: public key "Launchpad PPA for OndÅej Surý" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK
Then I ran apt-get update followed by apt-get upgrade, and just for
overkill, I ran apt-get dist-upgrade. These last 2 commands both state
that my system is up to date.
However, when I execute php -v, I still see 5.3.2-1ubuntu4.20.
My PHP is not upgrading to PHP5.5 as expected
What am I missing in order to upgrade the PHP to the version offered by
the PPA?