BSA B50 SS
... that the BSA B50 SS motorcycle proved its credentials by winning the 500 cc class in the Thruxton 500 and the Barcelona 24-hour endurance race?
... that the <b id="mwDog"><a href="./BSA_B50" id="mwDok" rel="mw:WikiLink" title="BSA B50">BSA B50 SS</a></b> <a href="./Motorcycle" id="mwDoo" rel="mw:WikiLink" title="Motorcycle">motorcycle</a> proved its credentials by winning the 500<span id="mwDos" typeof="mw:Entity"> </span>cc class in the <a href="./Thruxton_500" id="mwDow" rel="mw:WikiLink" title="Thruxton 500">Thruxton 500</a> and the <a href="./Barcelona" id="mwDo0" rel="mw:WikiLink" title="Barcelona">Barcelona</a> 24-hour endurance race?