The same Sir Charles Duncombe who presented the clock in 1709 three years later presented the organ.  It was built by Abraham Jordan, father and son, who announced in The Spectator of 8 February 1712 that one of the four sets of keys "is adapted to the art of emitting sounds by swelling the notes, which never was in any organ before" - the first 'swell organ'.  There is nothing left of the original swell organ as it has been since rebuilt.