5643
Having established its main operating base at Northolt BEA operated its first service from Heathrow in April 1950 ; by late-1954 all Northolt operations had moved to Heathrow which remained the airline's main operating base until the merger with  BOAC  in  1974  .
 None
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
Answer:
 NA: BOAC, 1974