To satisfy my curiousity, I found a
photo of Concorde in BOAC livery at the bottom of
this page of BOAC history.
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BOAC had been awaiting delivery of the Super Sonic Concorde by the 1970s and the advertising picture below shows it in BOAC livery. By 1975 when they were delivered BOAC had merged with its sister airline BEA to form the now world rated British Airways.</font>
from
http://airlines.afriqonline.com/airlines/560.htm