This photo is from page 11 of J.B. Wadley's 1972 collection Old Roads and New, in the chapter on cycling journalist Rene de Latour. Latour was a friend of, and frequently translator for Oppy. There is no photo credit for this image and no source indicated. The caption below is Wadley's:
Three years later [after Oppy's 1st major road race in Europe - Paris-Brussels, he placed 3rd] and now an established and popular star after couragous rides in the Tour de France, "Oppy" breaks away in the closing stages of the decennial Paris-Brest-Paris 750 miles marathon. He will be caught by a small group but [is] still strong enough to out sprint them on the final straight of the Velodrome Buffalo.
PBP Photos - 1931