Ntpdate

The ntpdate tool can be used to obtain the time from an Internet Time Server:

ntpdate -b ntp.blueyonder.co.uk

Using the cron
To configure the system to synchronize the clock with an Internet Time Server, every morning add the following entry to the /etc/crontab configuration file:

57     3    *   *   *           root      /usr/sbin/ntpdate ntp.blueyonder.co.uk
 * 1) minute hour dom mon day of week username command

Public Internet Time Servers
uk.pool.ntp.org (This points to a random UK based time server)