A former headmaster first of Higher Wych School, in Cheshire, then of Pleasey Hill School, in Nottinghamshire, Warrell, who was born in 1889, always believed in active learning. After earlier publications including the "Warrell-Way" series starting in 1946, he devised his first "I-Spy Spotterbook" in 1948, prudently taking the title from his devoted wife Marian in preference to his own more sober notion of calling the series "Learning from Life".
After failing with eight publishers, Warrell produced his little books by himself. He then chose his local branch of Woolworth's as a main outlet, drawing on a friendship with that firm's principal book-buyer based originally around a common interest in breeding pigs. Swift sales led to many more books, plus serialisation for two years in the Daily Mail and then, for a longer spell, in the News Chronicle. The whole series was to last till 1986, since when it has re-appeared under a succession of different publishing houses.
Warrell's I-Spy books combined simplicity of design with a great deal of accurate, often ingenious, research. Costing only sixpence, or a shilling in colour, each miniature paperback concentrated on a particular topic ranging from The Seaside to People in Uniform. Every one of the 40 or so pages inside would have a picture at the top followed by a short verbal description within which the author would share his own lively enthusiasms with his young audience. On the Allard JR2 sports car, for example, readers learn how "This model often uses a Cadillac engine of 51/2 litres! Wow!! Listen for the 'wuffle' as the car goes by!" Comment on a Buckler 90 is even more upbeat: "Build your own car? Why not!?"
But the real fun was still to come. For at the bottom of every page there was the inevitable I-Spyed challenge, in the case of the Allard for its "Faired head-rest and two exhaust pipes". An accurate sighting of these features, noting carefully both when and where in the appropriate box, was worth 30 points. If an unlikely full score of 1,500 points was scored after answering all the other I-SPY challenges in the book as well, then after a somewhat cautious authentication from parent or teacher ("I certify I have examined the record in this book, and as far as I can judge, the entries are genuine") a reader could send it to Wigwam-by-the-Water, London EC4. In return he or she would qualify for a Special Order of Merit franked by Big Chief's very own seal.
For those many children who never fulfilled demands to spot objects as rare as a mid- Victorian pillar-box, a nightingale or a four-leafed clover, easier ways were also available of gaining Big Chief I-Spy's special attention. For sixpence any "pale-face" was welcome to the Great Tribe of Red-skins, receiving in return an I-Spy badge and a code for deciphering the daily secret messages ("Odhu/ nttinggo") contained in Warrell's regular newspaper column. There was also a daily I-Spy pen to be awarded, plus the excitement of seeing one's own name in print, for particularly brilliant scores achieved in any one day. Moving up the I-Spy hierarchy, members could become Patrol Leader or Tally Book Keeper, organising their own meetings or patrol successes. Mass theatre outings were also organised, with 8,000 children on one occasion enjoying an I-Spy day out in London, travelling around in 80 hired double- decker buses.
Warrell's own favourite book was that on History. Parents, in their turn, increasingly bought those books best designed to keep children occupied first on train journeys and later in the family car. At its height, the whole I-Spy operation involved over 11/2 million young Red-skins, with two women assistants employed solely to answer members' numerous telephone and written questions.
Always happy to appear in his giant head-dress on special I-Spy pow-wows held at different parts of Britain, during which various tasks would be set followed by a grand session of prizegiving, Warrell eventually opted for a quieter life at his home in Budleigh Salterton, where he walked and gardened almost to the end. His birthdays in later years became something of a rallying point for Red-skins both young and old, happy to honour their still surviving Big Chief in his serene and well-earned retirement.
Charles Warrell, teacher, writer, publisher: born Farmborough, Somerset 23 April 1889; married Elizabeth Gill (deceased; two daughters), secondly Marian Tucker; died Matlock, Derbyshire 26 November 1995.