That's because you configured that yourself, on Ubuntu it shows this as an example.
[email protected]:~$ ls -l /etc/localtime
lrwxrwxrwx 1 root root 36 aug 16 20:24 /etc/localtime -> /usr/share/zoneinfo/Europe/London
If you actually configured the timezone according to the Arch Installation guide
you would have actually configured a Zone/SubZone. Unless you had a reason for using zoneinfo/GB?
I run Arch as well and I get the same as on my Ubuntu vm