I just happened to spot this browsing Time Out yesterday.
A drive-time concert of Mozart, Bizet and Piazzola at St Margaret’s Westminster today. I’m not sure what mix of instruments they are (presumably they include an accordionist given the Piazzola?). Go along and find out, at 6pm. Tickets £7 (concessions £5) from 020 7121 6604 and info from 020 7654 4841.
Link to St Margaret’s website (click on “Rush Hour Classics” for confirmation of the concert)