 The 83rd Boat Race took place on 21 March 1931 . Held annually , the Boat Race is a side @-@ by @-@ side rowing race between crews from the Universities of Oxford and Cambridge along the River Thames . In a race umpired by the former rower John Houghton Gibbon , Cambridge won by two and a half lengths in a time of 19 minutes 26 seconds . The victory took the overall record to 42 – 40 in their favour . It was the first race for which John Snagge provided a radio commentary for the BBC . 
