BBC Four (2002)

BBC Four launched on 2 March 2002 at 19.00 GMT, having been delayed from the original planned 2001 launch. The channel replaced BBC Knowledge, an educational and cultural channel which had undergone many changes throughout its lifetime; the latter of which consisted of documentaries and art programming: essentially a test of the new BBC Four schedule. BBC Four would rebrand this channel, and bring it into line with the well recognised BBC One and Two brands at the same time. Planning for the new channel, along with the new BBC Three, had been in progress since October 2000; however the incumbent government delayed approving the new BBC digital plans. The BBC Four plans were approved earlier, and as a result launched before BBC Three.

BBC Four was different from the old BBC Knowledge: the channel would be more heavily promoted with more new and original programming and the channel wouldn't be broadcast 24 hours a day. This is due to the fact that on the Freeview digital terrestrial platform, BBC Four is broadcast in a statistically multiplexed stream in Multiplex B that timeshares with the CBeebies channel. As a result, BBC Four broadcasts from 7 pm to about 4 am every day, with an hours down-time and promotions for CBeebies, before CBeebies channel runs from 6 am until 7 pm.

On 12 May 2011, BBC Four was added to the Sky EPG in Ireland on channel 230.