Ian Allan, new ed., 1986. 192 pp., numerous photo-ills., ills., maps & plans. D.j., 24 x 17cm. FINE. In 1969 No 1 Squadron RAF was introduced to its new mount, the revolutionary V/STOL Harrier GR1. Of course, vertical ascent and decent were not entirely new for the unit: No 1 Squadron RFC had been formed in 1912 from the airship-equipped No 1 Company, Air Battalion. It was with this historical parallel in mind that the author, one of those first Harrier pilots, published a history of the Squadron in 1971 entitled Twice Vertical. This new edition details No 1’s illustrious history from its ‘vertical prelude’ as a Balloon Section of the Royal Engineers through Flanders and Mesopotamia, through the Second World War Battles of France and Britain, to its operations in the Falklands War. With superb illustrations of this, the oldest military flying unit.