The Glasgow Socialist Women's Choir, led by Dolina McClellan, excels in this field. (They sang for Nelson Mandela when he visited the city.) I'm sure they'll have a tape or CD. Also, at the moving funeral of a lifelong Socialist I was at earlier in the year, The Internationale was sung by another choir - I think the tape in the crematorium came from the Euro MP Janey Buchan (widow of the late Norman Buchan, folksong enthusiast and collector.) I'll make further inquiries. Watch this space...