It’s a piece of library music called Grand Orchestral Fanfare by Gregor F Narholz and was released in 1996. From memory Fluff didn’t use it right from the start of the Radio 2 era of Pick of the Pops in 1997 but started a bit later on. Sponge Bob started in 1999 so I would like to think that maybe someone working on POTP heard it in an episode and thought it would be a good piece of music to use. Unfortunately the boring reality is probably that both the BBC and the Sponge Bob producers had the same CD of stock music.
The music is "At the Sign of the Swinging Cymbal" by Brian Fahey. He recorded it. The later version used is an arrangement by Barbra Moore and played by a session group calling itself Brass Incorporated. The version that is currently used by the BBC is an edit of Barbra Moore's version and is shorter. This version here is slightly longer than what is currently used and is another edit of the Barbra Moore version. Bother the Barbra Moore full version and the original Brian Fahey version are up on RU-vid.
The only presenters who could do a proper countdown to this were Alan Freeman and Tony Blackburn maybe Paul Gambaccini too. Wright has no idea and loves the sound of his own voice.
