I had no idea this was released as a song. It's three years old apparently, but pretty good...probably mentioned before, but just for anyone else who didn't know and is sad enough (like me) to buy BBC Music (BBC World the soundtrack is good too!!)...
Yeah it was out a few years back but didn't really get too much attention in the clubs. I suppose people didn't want to look stupid dancing to a BBC One ident.
It is indeed called "Forever And A Day" by an artist called "State One" - I got the CD single from HMV.co.uk a couple of years ago. According to the sleeve notes, it was inspired by the BBC One Ident music for festival, rather than the other way round. The lyrics are trite and sung by the usual female vocals found on many post-2002 trance songs.
http://netizen.myby.co.uk/music/forever.wma - I wouldn't waste your time if I were you though, the bit that sounds most like the Festival music is towards the end and very short. Maybe there's a better version to be had, I couldn't be bothered to look for it.