Simplify the following text for a Grade 10 native English-speaking person.
Original: His conducting debut with the London Philharmonic Orchestra ( LPO ) was in December 2001 . In 2003 , he was appointed the LPO 's Principal Guest Conductor and a member of the Russian National Orchestra Conductor Collegium He is also Principal Guest Conductor of the Russian National Orchestra , and a Principal Artist of the Orchestra of the Age of Enlightenment .
Simplified: He is now the Principal Conductor of the London Philharmonic Orchestra .