Question: What English composer/musician, known as the "Fifth Beatle," produced two records by British vocal group, The Master Singers?  
Sentence (from "George Martin"): Sir George Henry Martin {'1': ", '2': ", '3': ", '4': "} (3 January 19268 March 2016) was an English record producer, arranger, composer, conductor, audio engineer, and musician.
Relevant evidence: Yes