Pioneering engineer; Born January 8, 1916; Died May 20, 2007.

Sir George Macfarlane, who has died aged 91, was an engineering scientist whose ground-breaking work assessing the capabilities of radar aided the battles fought in the air during the Second World War.

Working under the inventor of radar, the Brechin-born Sir Robert Watson Watt, in the top-secret Telecommunications Research Establishment (TRE), Macfarlane and Watt had much time to make up, for before the Second World War, the government had concluded that there was no defence against attack by bombers, despite Watt's argument of detecting them "by radio energy bouncing back from the aircraft's body".

Macfarlane, an outstanding mathematician, showed himself an invaluable member of the TRE mathematical group in theoretical studies, his work ultimately demonstrating the effectiveness of ground radar to direct RAF fighters in the night blitz. He went on to advise the government on Window, the technique of dropping clusters of metallic strips to blind German radar systems, and played a hand in the development of Oboe, radar detection which vastly increased the accuracy of Bomber Command operations, as well as pioneering equipment used in detection of U-boats.

In 1945, he found it a matter of mild irony to be commissioned into the RAF as a squadron leader. At the outbreak of war, he had been turned down for the Royal Navy because his talents had been seen as essential to war effort at home. His move into uniform led to attachment to US forces to collect information from captured German radar systems and personnel.

He spent VE-Day in Paris, and watched the victory parade down the Champs Elysees, an event in which the figure ultimately heading the parade was 6ft Drum-Major Alec Wilson, from Turriff, Aberdeenshire.

Macfarlane's post-war career continued to reflect his exceptional talent. He was a key figure in what became the Royal Radar Establishment, taking over in 1971 as controller of the research establishment and research programmes at the Ministry of Defence.

George Gray Macfarlane was born in Airdrie, the youngest child of a grocer. His parents, strict Presbyterians, took their children to church twice on Sundays. Educated at Airdrie Academy, Macfarlane initially failed to shine.

What created the engineer in him, he recorded, was watching shipping passing up and down the Clyde while on holiday at Strone, Argyllshire. When shown the primitive wireless telegraphy apparatus aboard a cargo vessel, he recalled years later how aroused his imagination was by "this miracle".

He returned to Airdrie Academy fired up, stayed an extra year to improve his maths and, after graduation from Glasgow University in 1937, went to Dresden for further study at the Tchnische Hochschule, completing a doctorate just a fortnight before Hitler invaded Poland and war was declared.

A modest man, Macfarlane quickly learned as a youngster that self-effacement was no excuse for not being forceful when occasion demanded. It was this ability to make his point firmly, trenchantly and without malice that endeared him to Tony Benn, the Minister of Technology in the "white heat" of Harold Wilson's government. Macfarlane found Benn "stimulating", and worked well with him on managing the 23,000 staff in numerous R&D establishments.

Knighted in 1971, he served after retirement on the board of the Post Office, advising on introduction of optical-fibre and digital technology into the telephone system despite high staff resistance. Sir George, ever the proponent for radical change, welcomed the opportunity for this that privatisation brought, going on to become a board member of the new British Telecom.

He is survived by Barbara Thomson, his wife of 66 years, a son and daughter.