D-Day Daily Telegraph crossword security alarm

The D-Day Daily Telegraph crossword security alarm arose in 1944 when codenames related to the D-Day plans appeared as solutions in crosswords in the popular British newspaper, The Daily Telegraph. The inclusion of the codewords was initially suspected by the British Secret Services to be a form of espionage.

Background
Leonard Dawe, Telegraph crossword compiler, created those puzzles, at his home in Leatherhead. Dawe was also headmaster of Strand School, which during the Second World War was evacuated to Effingham in Surrey. Next to the school was a big camp of USA and Canadian troops getting ready for D-Day, and security round the camp was lax, and there was much contact between the schoolboys and soldiers, during which soldiers' talk including D-Day codewords was heard and learned by many of the schoolboys.

On 18 August 1942, a day before the Dieppe raid, 'Dieppe' appeared as an answer in a Daily Telegraph crossword (set on 17 August 1942) (clued "French port"), causing a security alarm. The War Office suspected that the crossword had been used to pass intelligence to the enemy and called upon Lord Tweedsmuir, then a senior intelligence officer attached to the Canadian Army, to investigate the crossword. Tweedsmuir, the son of John Buchan the author, later commented: "We noticed that the crossword contained the word "Dieppe", and there was an immediate and exhaustive inquiry which also involved MI5. But in the end it was concluded that it was just a remarkable coincidence – a complete fluke".

D-Day alarm
In the months before D-Day the solution words 'Juno', 'Gold' and 'Sword' (all codenames for D-Day beaches assigned to the British) appeared in Daily Telegraph crossword solutions, but they are common words in crosswords, and it was treated as coincidences.

Dawe had developed a habit of saving his crossword-compiling work time by calling boys into his study to fill crossword blanks with words; afterwards Dawe would provide clues for those words. As a result, war-related words including those codenames got into the crosswords; Dawe said later that at the time he did not know that these words were military codewords.

The run of D-Day codewords as Daily Telegraph crossword solutions continued:
 * May 1944: 'Utah' (clued as "One of the U.S."): codename for the D-Day beach assigned to the 4th US Assault Division (Utah Beach). This would have been treated as another coincidence.
 * 22 May: 'Omaha' (clued as "Red Indian on the Missouri"): codename for the D-Day beach to be taken by the 1st US Assault Division (Omaha Beach).
 * 27 May: 'Overlord' (codename for the whole D-Day operation: Operation Overlord)
 * 30 May: 'Mulberry' (Mulberry harbour)
 * 1 June: 15 Down was 'Neptune' (codeword for the naval assault phase: Operation Neptune).

Investigation and aftermath
MI5 became involved and arrested Dawe at the school, and arrested his senior colleague crossword compiler Melville Jones at his home in Bury St Edmunds, and interrogated them intensively, but decided that he was innocent; Dawe nearly lost his job as a headmaster over this. (He kept secrecy about the interrogation until he described it in a BBC interview in 1958.) Afterwards, Dawe asked at least one of the boys (Ronald French) where he had got those codewords from, and was alarmed at the contents of the boy's notebook, and gave him a severe reprimand about secrecy and national security during war, and ordered the notebook to be burnt, and ordered the boy to swear secrecy on the Bible; the boy kept this secrecy until 1984. The public were told that this leakage of codenames was coincidence.

In 1980 in a reader's letter to The Times an old pupil of Strand School owned up to having put codenames in the crosswords.

The truth emerged in 1984. Approach of the 40th anniversary of D-Day reminded people of the crossword incident, causing a check for any codewords related to the 1982 Falklands War in Daily Telegraph crosswords set around the time of that war; none were found. This induced Ronald French, then a property manager in Wolverhampton, to come forward to say that, in 1944 when he was a 14-year-old at the Strand School, he inserted D-Day codenames into crosswords, and how he had learned them. He believed that hundreds of children must have known what he knew.