From 1930 races on a smaller section of the track known as the 'Mountain Circuit' were introduced by the new Clerk of the Course, Mr A Percy Bradley. This fast and furious 1¼ mile lap running from the Fork to the rear of Members’ Hill and back, provided a cross between road and track racing. It was a tough course for the drivers and a stern test of acceleration, braking, and road-holding for the cars.
The popularity of Brooklands grew throughout the 1930s. In 1930 the Clubhouse was extended to accommodate the social appeal of race meetings and the BARC adopted the slogan ‘The Right Crowd and No Crowding’. Brooklands, which was still the preserve of the wealthy amateur, became a fashionable venue on the sporting calendar along with Henley, Wimbledon and Ascot. Members of the BARC were often members of the Brooklands Flying Club as well and the airfield was a lively part of the track. The Paddock was a busy place as popular heroes mingled with Club Members or those spectators who could afford a paddock transfer pass into the’ inner sanctuary’.
The Junior Car Club continued to hold races at Brooklands, and organise club days for trials and driving tests but was most famous for its big international race meetings. The Double Twelve Hour Race, came about because night time noise restrictions meant 24 hour racing was not permitted at Brooklands. The event was divided into two daylight sessions with the cars being locked up overnight. The International Trophy was held every year from 1933 until 1939, for the first time large and small cars started together and raced for 250 miles - the faster the car the more severe the course as it negotiated its 100 circuits. This race attracted great names like Captain Malcolm Campbell, Kaye Don, Earl Howe and Elsie Wisdom.
Until 1933, Brooklands was unchallenged as the only motor racing circuit in mainland Britain, but in that year the track at Donington Park in Derbyshire was opened for car racing. Further competition came with the opening of a road-racing circuit at the Crystal Palace, in South East London. Facing up to this the BARC decided to construct a new road circuit at Brooklands, providing the maximum road racing track possible, without intruding on the Outer and Mountain Circuits, the aerodrome or the famous sewage farm! The new circuit, designed by, and named after, Sir Malcolm Campbell zig-zagged its way across the centre of the motorcourse cleverly incorporating the old banked track. Opened in 1937 it proved popular with the increasing number of drivers who wanted to experience the thrills of this sport.
Records for the Mountain and Campbell Circuits were highly prized and both were eventually held by Raymond Mays, famous for his involvement in the development of the English Racing Automobile, or ERA. The ERA chassis was designed by Reid Railton and made by Thomson & Taylor at Brooklands.