The winning bid for the historic machine at H&H Classics' sale at IWM Duxford on October 23 matched the hammer price of another Superior (an SS100 dating from 1929) sold by the same firm two years ago.
However with the buyer's premium now 12%, the buyer paid £291,200 as compared to £286,000 in 2009 when the premium was 10%.
George Beale, principal of H&H's motorcycle department, described it as "the most important British motorcycle ever built". The estimate was £250,000-270,000 and there were four serious bidders on the day.
This Superior, with a 1000cc side valve 'V' twin engine, was custom-built for the personal use of George Brough, founder of Brough Superior Motorcycles. He rode it for his first win at Brooklands (it was the first side-valve machine to lap the Surrey track at over 100mph) and racked up 51 victories in 1922-23 when he rebuilt the bike for sprinting and hill-climbing.
A burst tyre cost him the 52nd race and he had to sell the bike after a crash kept him in hospital and he had to pay the wages of his workers.
By now a bike first dubbed Spit and Polish was known as Old Bill. It was converted to road trim and was damaged in the Second World War during the Blitz when a cast-iron bath fell on it. In the late 1950s it was owned by 'Titch' Allen, founder of the Vintage Motorcycle Club, and restored to its 1923 condition with the assistance of George Brough.
In 1959 George actually rode it again on the same stretch of road where he had his accident 36 years earlier - this time staying on.
'Titch' gave the bike to his son Roger in 1988, who raced Old Bill in the TT races in 1991 (the first time a Brough had ever competed on the Isle of Man). Roger was killed on a Triumph machine when he crashed competing on the island in 1992. His collection passed to his widow and it had been on show at Nottingham Industrial Museum until she decided to sell.