Simplify the following text for a Grade 14 native English-speaking person.
Original: The Royal Philharmonic Society decided not to engage the RPO for its concerts in 1963 , Glyndebourne engaged the London Philharmonic instead of the RPO from 1964 onwards and the management of the Royal Festival Hall also severed its connections with the orchestra .
Simplified: In 1963 the Royal Philharmonic Society decided they would stop asking the RPO to play for their concerts , and in Glyndebourne , where the RPO had played for the opera since 1948 , the London Philharmonic Orchestra became the resident orchestra instead .