An entertaining programme aimed at a younger audience is provided by this afternoon's concert, of which BBC1 is transmitting the first half live. Raymond Leppard conducts the BBC Symphony Orchestra in Britten's ever-popular The Young Person Guide to the Orchestra, followed by Dohnanyi's charming Variations on a Nursery Song. David Owen Norris , piano soloist in the Dohnanyi, comments: "I like musical jokes and this one, like all the best jokes, should not be given away. There can be nothing more important than a concert designed for a younger audience. My children - Barnaby, 6, and Josiah, 4 - will be there to share it. And the joke." Introduced by James Naughtie from the Royal Albert Hall in London.