Never seen Rovers with a crest on the shirt until around the late eighties/early nineties. It was the shirt sponsored by Thorn Emi. Although on programmes they would use the one you have pictured above. There is another one floating around here that could have been possibly used during the fifties, Sligoman was using it as an avatar. Any of the old photographs on the net, wining league side 1977 or the '83 cup side have no crest on their shirts.