Historical Rock Poster from 1977 - Foreigner

I went to this concert in london when i was 14. this small poster is pretty unusual though. it was one of the first concerts ever by Foreigner - who is certainly not a big favorite of mine, but one of the best-selling bands in history. the venue was a wonderful place at the time. one week later, bob marley played there for his famous exodus concert. i wonder if this little, nondescript poster is worth anything?