ERA was established in November 1933 with the express purpose of upholding British prestige in Continental European racing, targeting the voiturette class — the Formula 2 equivalent of the day — rather than the prohibitively expensive full Grand Prix category. The company's cars were built around a chassis conceived by Reid Railton and constructed by Thomson and Taylor at Brooklands. The engine derived from a Riley six-cylinder unit, substantially modified with a forged crankshaft, new aluminium cylinder head, and a bespoke supercharger designed by Murray Jamieson. In its 1500 cc form the engine produced around 180–200 bhp, running on methanol.
The A Type, whose first chassis R1A was unveiled at Brooklands on 22 May 1934, quickly demonstrated its competitiveness, scoring notable victories against more established marques before the year was out. At the Nürburgring in 1935, ERAs took first, third, fourth and fifth places in a major race — a result that confirmed the formula was working. Four A Types were built with engines ranging from 1.1 to 2.0 litres.
Production of the B Type began in 1935, the car being a minimally changed development of the A Type. Like its predecessor, the B Type was offered with three engine sizes spanning the same 1.1-, 1.5-, and 2.0-litre range. The layout retained the same fundamental architecture — a ladder-frame chassis with the supercharged Riley-derived engine — that had already proven itself in competition.
Thirteen B Type ERAs were produced in total. Three of these were subsequently modified to later specifications: two to C Type standard and one to the unique D Type standard.
Among the most celebrated B Type campaigns was that of the two Siamese princes, Chula Chakrabongse and Bira Birabongse. Prince Chula, whose family wealth financed the operation, bought an ERA for his cousin Prince Bira as a gift, and the pair ran their own private team from The White Mouse Garage in Hammersmith. Their trio of cars — named Hanuman, Romulus, and Remus — became famous as a distinctive and consistently competitive private entry at a time when ERA was dominating voiturette racing. Bira served as the driver while Chula managed the team.
Through the second half of the 1930s, ERAs — with the B Type at the core of the fleet during the peak seasons — dominated voiturette racing across Europe. The cars benefited from drivers of the calibre of Dick Seaman. The combination of competitive engineering, committed private operators such as the White Mouse team, and the sustained factory development effort made ERA the dominant force in the class.
The B Type participated across the major voiturette events of the era, accumulating a broad record of victories and podiums that cemented ERA's reputation as the leading British constructor in the pre-war formula car category.
The B Type formed the bridge between the original A Type and the more developed C Type that appeared in 1937. The C Type introduced a revised engine range — dropping the smallest 1.1-litre option and adding a 1.75-litre intermediate — as well as significant suspension upgrades: hydraulic rear dampers and a new front suspension replacing the earlier elliptic leaf springs with a trailing-arm, transverse-torsion-bar arrangement.
The D Type designation was applied to a single car, R4B, after further modification in 1938 — that chassis having already passed through C Type specification. The E Type that appeared just before World War II represented a more thorough redesign, though only one car raced before the conflict halted European motorsport entirely.
The vast majority of pre-war ERAs, including surviving B Types, remain in existence today with continuous and verifiable provenance. They continue to compete in historic events and are particularly associated with the Shelsley Walsh hillclimb, where Raymond Mays won the first two British Hill Climb Championships in 1947 and 1948.