The race operated on a class handicap system. Cars were released in staggered intervals based on engine capacity and anticipated performance, with the slowest class — typically cars under 750 cc — departing first. Scratch cars, the fastest entries, started last after as much as 78 minutes had elapsed. The winner was determined on corrected time, meaning a small-engined car that managed its handicap correctly could beat a much faster outright machine. This format produced dramatic finishes in which the race outcome was often unknown until the final laps.
The inaugural race in 1929 was won by Frank Clement and Jack Barclay in a 4.5-litre Bentley on handicap, though the fastest pairing was Sammy Davis and Clive Dunfee in a Bentley Speed Six. Davis returned to win again in 1930, this time paired with the Earl of March in a 747 cc Austin 7, averaging 83 mph despite poor weather conditions early in the race — a result that illustrated just how emphatically the handicap system could favour small-engined entries.
By 1931 the race had "become firmly established as one of the leading events of the racing calendar" and began attracting continental competitors, including Freddy Zehender, Stanislaus Czaykowski, Juan Zanelli, and Per Wiktor Widengren. That year Jack Dunfee and Cyril Paul won outright and on handicap in a 6-litre Bentley "Old Number One," setting a world speed record of over 118 mph.
The 1932 race brought both triumph and tragedy. Ron Horton and Jack Bartlett won in Horton's streamlined 746 cc MG Midget, but the day was marred by the death of Clive Dunfee, who went over the top of the Members' Banking in an 8-litre Bentley. Bartlett had to swerve around the body; the prize money went to Horton as car owner, with Bartlett receiving only a commemorative plaque.
In 1933 Eddie Hall won solo in a streamlined MG Magnette, disciplined pitting minimising his time off the circuit. His girlfriend Joan managed his schedule from the pits. The race was briefly stopped following a fatal accident involving Michael Bower Watson, whose MG caught fire after overturning during a refuelling stop. Freddie Dixon emulated Hall's solo strategy in 1934 in a 2-litre Riley, taking the lead only two laps from the finish after the leading works Riley shed an exhaust.
The 1935 race fell to the enormous Napier-Railton special, its 24-litre engine purpose-built for Brooklands' banking. John Cobb and Tim Rose-Richards averaged over 121 mph. That year also marked the first time women were invited to compete: Gwenda Stewart, Doreen Evans, "Bill" Wisdom, and Kay Petre all entered, with Wisdom the only woman still running at the finish.
By 1936, manufacturer interest was fading. The gruelling nature of the event, the ageing bumpy surface at Brooklands, and the format's increasingly specialist character had eroded the entry list as manufacturers focused their attention on road racing circuits. Only 18 cars started the 1936 race, and just six were still running at the finish. Dixon and Charlie Martin won again in a 2-litre Riley.
To revive interest, the 1937 race was shortened from 500 miles to 500 kilometres, and the winning speed of over 127 mph made it the fastest the event had ever been. The meeting was overshadowed, however, when Kay Petre was seriously injured in practice after her Austin 7 was struck broadside by Reg Parnell's MG Magnette.
The race was not held again. In September 1938 the BRDC announced it would replace the 500-mile (or kilometre) event with shorter races, and Brooklands itself closed the following year as it too was requisitioned for wartime use.
The International 500 Miles Race was the most important long-distance motor race in Britain during the interwar period and one of the fastest events anywhere in the world at its peak. Its handicap format encouraged technical diversity and produced unpredictable results that rewarded strategy alongside speed. The race reflected both the unique character of Brooklands — a banked oval unsuited to the road-racing formula that came to dominate the sport — and the breadth of British motorsport culture in the 1930s, from giant Bentleys and Napier-Railton specials to tiny MG Midgets winning on corrected time.