This file contains a list of every IPv4 address with reverse DNS ending in .gov.uk. There's some interesting things in here.
If you like this, you may also like my list of UK government web proxies.
109.104.88.83 ola.kent.gov.uk
109.104.88.84 ola.kent.gov.uk
109.176.74.7 filter.torbay.gov.uk