Does what it says on the tin. While it starts from a basic state of being quite amusing, enjoyment increases proportionate to your familiarity with (a) who Servalan was and (b) the music of Pink Floyd. If you're reasonably familiar with Blake's 7 (there's a clue to (a)) then an extra gag kicks in at 48 seconds.
In researching that - thanks to the latest issue of SFX for the pointer - I also came across this little gem which, I dunno, spoke to me somehow. Again, enjoyment increases proportionate to familiarity with the key players.