Detailed Instructions: In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it. Your job is to determine which sentence(s) from the passage can be used to search for further information needed to answer the question.
Q: Question: How many members did the BBC Philharmonic Orchestra have when Walker conducted it in the summer of 2010? Passage:In 2000/01 Walker conducted the English Touring Opera's production of the Magic Flute, and on 27 November 2004 the Chelsea Opera Group (UK) in Glinka's A Life for the Tsar at the Queen Elizabeth Hall. In November 2005 he conducted the Prague Philharmonia, and in the winter season 2005/6 Walker conducted three performances of The Nutcracker for the Royal Opera House, Covent Garden, and Swan Lake in 2009 for the Finnish National Ballet. On 4 July 2010 he conducted the BBC Philharmonic Orchestra, and in 2011 a concert with the Royal Philharmonic Orchestra. He appeared at the Oundle International Festival in 2011 where he conducted the premiere of Prophet and Loss by Julian Grant. In October 2011 he conducted a Gershwin Gala with the Russian Philharmonic. In 2012 Walker conducted the English Chamber Orchestra. and a production of the Nutcracker at the Norwegian National Opera and Ballet. On 19 April 2015 he conducted the New Russia State Symphony Orchestra. In 2017 he was awarded the Elgar Medal by the Elgar Society for championing the composer's music internationally in countries including Belarus, Russia, Poland, Turkey and Romania.

A:
On 4 July 2010 he conducted the BBC Philharmonic Orchestra, and in 2011 a concert with the Royal Philharmonic Orchestra