Simplify the following text for a Grade 8 native English-speaking person.
Original: The group gave its first performance as the Amadeus Quartet at the Wigmore Hall in London on 10 January 1948 , underwritten by Imogen Holst .
Simplified: The group gave its first performance as the Amadeus Quartet in the Wigmore Hall , London on Jan. 10 , 1948 .