Birkin was born into a wealthy Nottingham family in 1896, the son of Sir Thomas Stanley Birkin, 2nd Baronet. As a child he acquired the nickname "Tim" after the comic-book character Tiger Tim, and the name stayed with him for life. He served with the Royal Flying Corps during World War I, reaching the rank of Lieutenant and serving in Palestine, where he contracted malaria — an illness that would recur and contribute to his death. He married Audrey Clara Lilian Latham in 1921; the couple divorced in 1928 and had two daughters.
Birkin turned to motor racing in 1921, competing at Brooklands. Family and business pressures forced a pause until 1927, when he returned with a three-litre Bentley. He performed well enough that by 1928 he had joined the Bentley works team and was regularly racing with a blue and white spotted silk scarf around his neck — a look that became iconic.
At Le Mans in 1928, Birkin led the opening twenty laps before a jammed wheel forced him to fall back; he finished fifth. In 1929 he won outright alongside Woolf Barnato in the Speed Six.
His most celebrated contribution to the sport, however, was the supercharged Bentley project. Convinced that more power from a lighter car — rather than raw displacement — was the path forward, Birkin pursued the idea of fitting a Roots-type supercharger to the 4½-litre Bentley after Bentley Motors declined to develop it. With technical assistance from Clive Gallop and supercharger specialist Amherst Villiers, and financial backing from Dorothy Paget after his own funds ran out, Birkin built the "Blower Bentley" at a workshop in Welwyn Garden City. The resulting car produced 242 bhp and had a distinctive, unmistakable appearance with the supercharger mounted ahead of the radiator. W. O. Bentley himself never believed in the project, but Birkin persuaded the company to produce fifty road cars in order to qualify the supercharged version for Le Mans.
At Le Mans in 1930, the blower Bentleys waged an epic battle with Rudolf Caracciola's Mercedes SSK. Birkin famously harried Caracciola into submission — driving at the absolute limit to pressure the German driver — before all three cars retired, leaving the works Speed Six to take victory. His selfless aggression in that duel has come to symbolise the spirit of Vintage Racing.
After Bentley Motors withdrew from racing in 1930, Birkin's situation became difficult. Dorothy Paget withdrew her team support in October of that year, and while she continued backing Birkin's individual track car — a re-bodied Blower No.1 nicknamed the "Brooklands Battleship" — broader opportunities contracted. Birkin kept his workshop open in partnership with Mike Couper, developing high-performance cars, though this arrangement ended in 1932.
Despite these setbacks, Birkin continued to win. In 1931 he took Le Mans victory with Earl Howe, driving an Alfa Romeo rather than a Bentley. The win prompted a telegram from Mussolini congratulating him on a "win for Italy." On 24 March 1932 Birkin raised the Brooklands Outer Circuit lap record to 137.96 mph in the Battleship — a record that stood until John Cobb's Napier Railton broke it two years later.
Birkin was not confined to endurance racing. He competed in various Grand Prix events and scored a notable second place at the 1930 Grand Prix of Pau, driving his Blower Bentley against a field dominated by Bugattis. His use of the car's horn to warn a Bugatti driver to move over is regarded as a unique moment in Grand Prix history. He also competed at the Tripoli Grand Prix in May 1933, finishing third in a Maserati 8C.
During his pit stop at Tripoli on 7 May 1933, Birkin burned his arm badly on the exhaust pipe while reaching for a cigarette lighter. The wound became infected, and combined with a recurrence of malaria, the injury proved fatal. He died on 22 June 1933 at a nursing home in London, aged thirty-six. He was buried at St Nicholas Church, Blakeney, Norfolk. His baronetcy passed to his paternal uncle Sir Alexander Russell Birkin, 4th Baronet.
Tim Birkin's legacy rests on three pillars: the Blower Bentley project, which created one of the most charismatic racing cars of the interwar period; his Le Mans victories in 1929 and 1931; and the fearless, attacking style that made him a hero to crowds at Brooklands and Le Mans alike. His life was dramatised in the 1995 television film Full Throttle, with Rowan Atkinson portraying him. Bentley later honoured him with the limited "Birkin Arnage" edition of 54 cars in 2000. The Blower Bentley he created continues to rank among the most recognisable and storied racing cars in British motorsport history.