Complex sentence: On 4 June 2012 Lennox performed, as part of the Queen's Diamond Jubilee Concert, in front of Buckingham Palace in London and on 12 August she performed "Little Bird" at the 2012 Summer Olympics Closing Ceremony.
Split into simpler sentences: On 4 June 2012, Lennox performed as part of the Queen's Diamond Jubilee Concert in front of Buckingham Palace, London. On 12 August 2012, Lennox performed "Little Bird" at the 2012 Summer Olympics Closing Ceremony.