Description: This is one of my favorite Observed Trials motorcycles, HNP 331.
The cycle pictured is HNP 331 in it's last form. The bike started life as a 1950 model but in this photo has magnesium alloy engine cases, aluminum alloy cylinder barrel and a late 50's frame and petrol tank as ridden by Johnny Brittain in the 1957 Scottish Six Day Trials (SSDT).
Johnny Brittain joined Royal Enfield in 1950 and his countless Fifties’ successes on his works machine carrying the registration HNP 331 made him a trials legend.
Royal Enfield demonstrated its products’ rugged reliability in observed and long-distance trials. The company adopted a swinging arm frame in 1948 when rigid frames were the norm for observed trials competition and its 350cc single cylinder engine provided all the power needed to negotiate tricky observed sections. Brittain’s achievements on HNP 331 included winning both the British Experts' Trial and the Scottish Six Day Trials. He won the Scottish Six Day Trials in 1952 and 1957.