Richard Marquand was born on April 22nd 1938 in Cardiff, Wales.  He was a director and writer for movies such as Jagged Edge and Eye of the Needle.  His biggest movie however was taking the director's chair for one of the biggest movies of the 20th century, Return of the Jedi.  

Having a studio as big as Pinewood Studios coming to Cardiff, their history associated with Star Wars and Marquand being from Cardiff I think its only fitting to have a soundstage named after the director.