How to change the time zone of a server in CentOS server

----------------------------------------------------------------------------------------------------------------------------
[root@test ~]# ls -al /etc/localtime
lrwxrwxrwx 1 root root 33 Aug 20  2012 /etc/localtime -> /usr/share/zoneinfo/Europe/London
[root@test ~]# cat /etc/sysconfig/clock
ZONE="Europe/London"
[root@test ~]# cat /etc/issue
CentOS release 6.3 (Final)
Kernel \r on an \m
----------------------------------------------------------------------------------------------------------------------------