Published by The Stationary Office (TSO), the London Gazette, Belfast Gazette and Edinburgh Gazette are the official newspapers of record in the United Kingdom. As such, they contain a wealth of notices and tidbits of interest to genealogists, including obituaries and death notices, notifications of military awards and medals, and insolvency and other legal notices. The Gazettes-Online Web site now offers free access to digitized archives from all three papers. All Gazette notices and supplements are already available online, along with a full historical archive of the 20th century. The TSO is currently in the process of digitizing the rest of the newspaper archive back to 1665, soon to be available online.

The recent upload of 167 years of the Gazette archive has caused some unanticipated technical issues and search is a bit dicey right now. The TSO recommends that you re-visit the site the week of October 16th if you're having problems. And don't let the big city locations put you off. I was able to find some interesting tidbits on my husband's ancestors in Bristol and Nailsea.
Gazette Online Archive Search

Related: Family History in the News - How to Find & Use Old Newspapers for Genealogical Research