This trend was accentuated by Le Queux, who collected 'sightings' brought to his attention by readers and raised them through his association with the Daily Mail. Subsequent research has since shown that no significant German espionage network existed in Britain at this time. Claims about the scale of German invasion preparations grew increasingly ambitious. The number of German spies was put at between 60,000 and 300,000 (in spite of the total German community in Britain being no more than 44,000 people). It was alleged that thousands of rifles were being stockpiled by German spies in order to arm saboteurs at the outbreak of war. Calls for government action grew ever more intense, and in 1909 it was given as the reason for the secret foundation of the Secret Service Bureau, the forerunner of MI5 and MI6. Historians today debate whether this was in fact the real reason, but in any case the concerns raised in invasion literature came to define the early duties of the Bureau's Home Section. Vernon Kell, the section head, remained obsessed with the location of these saboteurs, focusing his operational plans both before and during the war on defeating the saboteurs imagined by Le Queux. Invasion literature was not without detractors; policy experts in the years preceding the First World War said invasion literature risked inciting war between England and Germany and France. Critics such as Prime Minister Henry Campbell-Bannerman denounced Le Queux's The Invasion of 1910 as "calculated to inflame public opinion abroad and alarm the more ignorant public at home." Journalist Charles Lowe wrote in 1910: "Among all the causes contributing to the continuance of a state of bad blood between England and Germany perhaps the most potent is the baneful industry of those unscrupulous writers who are forever asserting that the Germans are only awaiting a fitting opportunity to attack us in our island home and burst us up." Notable invasion literature Pre-World War I Coming events cast their shadows before.” A history of the sudden and terrible invasion of England by the French, in the month of May, 1852 (1851) by an unknown author The Invasion of England – A Possible Tale of Future Times,(1870) by Alfred Bates Richards The Battle of Dorking (1871) by George Tomkyns Chesney Chapters from Future History: The Battle of Berlin (1871) by M. R. McCauley The Invasion (1877) W. H. Walker A Catástrofe (ca. 1878) by