In Widening Horizons, the fourth volume of his monumental history of British aviation, Harald Penrose deals with the traumatic years, 1930 to 1934. These were the distressing times of world economic depression, when unemployment figures reached heights quite unacceptable today. They were hardly years in which one would expect civil aviation, a new industry, to flourish. And yet it did, particularly in the drawing offices and the factories of great British aero companies like Handley Page, Hawker, de Havilland and Vickers.

It was an age of pioneers who knew their aeronautical design to the last nut and bolt, big men who stimulated almost unlimited enthusiasm, ingenuity, and loyalty among their staff, who established civil aviation as a major and permanent feature of the transport world but who never forgot Britain's need for a military aircraft capability. They provided Britain with the aircraft to compete with potential adversaries; out of the Schneider Trophy winning seaplane of 1931 was born the Spitfire, destined to be the crucial fighter in five years of war against Nazi Germany.

Harald Penrose, whose earlier volumes gave an unrivalled exposition of the first decades of flying, once more fulls out the expanding canvas of the aviation scene. Nothing of value is omitted: summaries of parliamentary debates on civil and military aviation needs and responsibilities, boardroom rows among the giants of the industry, epic achievements like the flight over Mount Everest (in which the author played a key role in test-flying the aircraft eventually used), pioneering works by people like La Cierva of Autogyro fame, Barnes Wallis (later to become one of the greatest names of aviation), R. J. Mitchell of the Spitfire concept, Amy Johnson and her spectacular career, all is there. And it is told in the fast-flowing and intimate Penrose style, carrying the racing tale along, supported all the way with the authority of a professional specialist in a variety of aeronautical fields. And it is illustrate with evocative pictures of nearly 100 aircraft — biplanes, monoplanes, seaplanes, civil and military — which are now part of aviation history.