Connaught had originally planned to build a streamlined Grand Prix car around the 2.5-litre Coventry Climax FPE "Godiva" engine. When that engine project was abandoned, the team switched to the Alta straight-four unit. The streamliner body concept was also rejected on practical grounds: drivers found it caused similar difficulties to those encountered with the Mercedes-Benz W196 streamliner, making it impossible to place the car accurately at corner apexes. Conventional, close-fitting bodywork replaced it.
Seven Type B chassis were constructed between 1954 and 1958. Each used a conventional space-frame structure on a tubular chassis, with independent front suspension via wishbones and torsion bars, and a de Dion rear axle. Disc brakes were fitted at all four corners. The cars were powered by 2.5-litre Alta four-cylinder engines producing 250 bhp, transmitted through a four-speed preselector gearbox.
The Type B made its competitive debut at the 1955 Glover Trophy, where Tony Rolt qualified fifth but retired after eight laps with a faulty fuel pump. Early results in championship races were discouraging: at the 1955 British Grand Prix all five Connaught entries failed to finish. Owner Kenneth McAlpine considered closing the operation.
The team's fortunes changed dramatically at the non-championship 1955 Syracuse Grand Prix in Sicily. Drawn by the substantial starting money on offer from the organisers, Connaught entered two cars for Tony Brooks and Les Leston. Brooks won by a margin of 50 seconds over Luigi Musso's works Maserati 250F — a result that astonished the paddock. It was the first British victory on a Continental European track in over thirty years.
Despite the Syracuse triumph, the Type B continued to struggle against the dominant Maserati 250F and the increasingly competitive Vanwall in World Championship events. A restricted programme across three subsequent seasons — just five championship races in total — yielded a best of third place, achieved by Ron Flockhart at the 1956 Italian Grand Prix at Monza.
In domestic UK racing, the car was more competitive. Archie Scott Brown won the 1956 BRSCC Formula 1 Race, and Stuart Lewis-Evans took victory at the 1957 Glover Trophy.
The Type B made its last World Championship appearance at the 1958 British Grand Prix at Silverstone, by which time the team was being run by Bernie Ecclestone. Both cars entered that race retired. The financial constraints that had always hampered Connaught Engineering ultimately proved insurmountable, and the team ceased operations.
The Connaught Type B occupies a specific and significant niche in British racing history. The Syracuse victory in 1955 demonstrated that a small, privately funded British constructor could match the established European works teams on their home ground, arriving just as a wave of British constructors — Vanwall, BRM, Cooper, Lotus — were beginning to transform Formula One's competitive landscape. The car's victory, achieved against the odds by Brooks with minimal resources, remains one of the more unlikely results of the mid-1950s Grand Prix era.