In this paper we explore the hypothesis that the blue progenitor of SN 1987A was a component of a close binary. It is shown that a blue spectral appearance at the end of core helium burning (and possibly also during the following evolutionary phases) is a natural phenomenon for a star with initial mass between 9 M⊙ and 15 M⊙ which was originally in a close binary with mass ratio q ≍ 1 and who accreted at least 8 – 10 M⊙ while already being a hydrogen shell burning star. This phenomenon does not depend on the exact treatment of the convective core overshooting, the stellar wind mass loss rate, and the metallicity. A blue SN progenitor in the Galaxy would therefore be a surprise.