Fortunately an unsung Luxembourg hero, W. Scholtes, the chief engineer at Junglinster, happened to know that a complete set of reserve valves was held at a nearby post office. McLean soon had Radio Luxembourg ready for service again on its wavelength of 1295m.
A mixed military and civilian team of amateur American psychological warriors attached to 12th Army Group were the first programme men on the scene. They belonged to the Office of Strategic Services (OSS), the forerunner of the CIA. An experienced Anglo-American group was sent to Luxembourg to broadcast on behalf of PWD Shaef - shortly afterwards augmented by a strong contingent from the BBC's European Service.
The OSS men took the line that they had saved the station and they resented being overshadowed by professional broadcasters who had not. Moreover they wanted to start a purely American enterprise, which they called "Operation Annie", using the transmitter for "black" propaganda purporting to come from dissidents within Germany. The PWD Shaef people, especially the British, considered that this scheme would endanger the credibility of the Allies' open or "white" broadcasts.
One of the OSS commanders asked McLean whether it would be possible to use the Junglinster transmitter on a different wavelength during the night after Radio Luxembourg had closed down. By when could they know whether it was technically feasible and how long would it take to alter the wavelength each time?
Within three days McLean provided the answers. It could be done and the wavelength change would only take 20 minutes. So "Operation Annie" went into action. At midnight an oboe signature tune introduced a strong new station calling itself Radio Twelve Twelve (the changed wavelength) to broadcast until 5.30am. It ran until the end of hostilities. McLean's solution pleased the OSS men and relieved the PWD Shaef contingent at Luxembourg - which I was shortly to join - of the pressure to carry "black" transmissions alongside straightforward ones. McLean himself had the satisfaction of knowing that he had done in three days what would take BBC engineers by normal procedures many weeks to achieve. Whether Radio Twelve Twelve deceived the German authorities or shortened the war by a single minute is another matter.
McLean, who was an accomplished linguist, brought to his Shaef task substantial experience of collaboration with European engineers. After graduating from Birmingham University he joined Western Electric and worked for three years on the design of high-power radio transmitters before being transferred to IT&T's Research Laboratories in Paris. From 1928 to 1932 he was involved in designing high-power equipment for both broadcasting and telephone transmission in Italy, Switzerland, France, Czechoslovakia and Hungary. In 1930 he married Dorothy Blackstaffe. They had known each other since their early teens.
On their return to England McLean's design work was particularly concerned with the BBC's short- and medium-wave transmitter equipment and in 1937 he joined the corporation's Station Design and Installation Department as head of the radio section. He was temporarily sent in 1938-39 to the Cavendish and Liverpool laboratories to help on problems connected with the atom-splitter cyclotron. From 1939 to 1943 he was deeply involved in the BBC's wartime expansion of short-wave transmissions and monitoring stations.
He also designed transmitters for the War Reporting Unit, and in 1943 was seconded to the Psychological Warfare Division of Shaef as Chief Engineer. In the planning of "Overlord" he made preparations for mobile transmitters as well as for recommissioning European radio stations. In August 1944 he was the first BBC man to enter Paris after its liberation, even ahead of the war correspondents. He reactivated various French transmitters before moving on to Luxembourg. Later in the war he recommissioned transmitters in Leipzig, Hamburg and other captured German cities, putting to good use the information on the location of spare valves he had gathered at Junglinster.
After the war McLean's career was a steady climb up the ladder of the BBC engineering directorate to the very top. Though necessarily interested in programmes his chief concern and fascination was always in technical developments. He retained his international connections, journeying in 1946 to Singapore to plan the BBC's Far East Relay Station, and later to the Indian sub- continent as an adviser to Radio Pakistan. From 1952 he led the BBC delegations to many international conferences on channel allocation, frequency modulation (FM), stereo and, above all, colour television.
As early as 1953, McLean read a paper to the British Association on "The Application of Colour to Television Broadcasting". In 1966 he delivered a Faraday Lecture on the same subject to large audiences in 23 cities in the United Kingdom and to one in Brussels, where he spoke in French. The same year he was invited to give the Granada lecture at Guildhall on telecommunications in the next 10 years. This ITV gesture represented the first thaw in the cold war between the BBC and its commercial competitor.
McLean recognised that the principal technical problems of television at that time were to define and achieve good colour, to plan the new 625- line UHF network (first used in 1964 for BBC2) so as to permit the eventual closure of the original 405-line VHF network, and to make possible the unattended operation of transmitters and studio equipment. He played a leading role in solving all of them.
By the time McLean became Director of Engineering in 1963 the introduction of colour television was high on the broadcasting agenda. One difficulty was the absence of an internationally agreed system. The Americans had established NTSC - the initials of the National Television Systems Committee, though cynics said the letters could equally stand for Never Twice the Same Colour. The French come along with SECAM, a different system of colour transmission which, like NTSC, was receivable on black-and-white sets, but claimed certain advantages over it. The rival merits of NTSC and SECAM were argued at many international forums, with McLean firmly on the side of NTSC. Then the Germans developed PAL, basically NTSC but with certain additional features. This was the system much of Western Europe eventually adopted.
The world's colour television was then split three ways, with Canada, the United States and much of Latin America, plus Japan, committed to NTSC; half of Europe, including Britain and Germany, and much of the Commonwealth committed to PAL; and France, the Communist bloc and some others committed to SECAM, threatening to make the ready international exchange of programmes impossible. Fortunately such a fate was avoided by the timely BBC invention of the electronic standards converter.
Sir Francis McLean (he was knighted in 1967) described this sophisticated equipment as "the result of both inspiration and hard work - the secret of engineering development". It converted systems as well as standards, and was thus able in 1968 to provide European television with an Olympic Games service of PAL or SECAM colour pictures on the 625-line 50-field standard which originated in Mexico from NTSC cameras working on the 525- line 60-field standard. The absence of internationally agreed system and standards had ceased to matter.
McLean gave the greatest encouragement to design development and research. He had a first-class brain and probably made a greater contribution to the BBC than any previous Director of Engineering. He was a stern but fair boss who disliked privilege and grumbled when he was accorded VIP treatment.
After his retirement from the BBC in 1968 he became the technical director of a company set up by ICI and CBS to develop a system of television recording and in 1972 he chaired a Royal Commission on FM Broadcasting in Australia. His report was accepted and implemented by the Australian government. From 1961 to 1972 he was Chairman of the BSI Telecommunications Standards Committee.
McLean's retirement also changed his life style. He and his wife moved to Newbury. Alongside his professional work he spent 10 years raising sheep on a small farm. He became the President of the Newbury District Field Club, a century-old society concerned with local history and the like. In 1978 they moved to nearby Woolton Hill, where McLean in his eighties produced very acceptable white wine from his garden, while still taking a lively interest in the latest developments in broadcasting and telecommunications.
Francis Charles McLean, broadcasting engineer: born 6 November 1904; Chief Engineer, Psychological Warfare Division, Shaef 1943-45; MBE 1945, CBE 1953; Deputy Chief Engineer, BBC 1952-60, Deputy Director of Engineering 1960-63, Director of Engineering 1963-68; Kt 1967; married 1930 Dorothy Blackstaffe (one son, one daughter); died 19 December 1998.