SW - AD Scout (Sparrow)

In the first years of WW1, British cities were endangered by attacks of German zeppelins. For this reason British Admirality (which job zeppelins were in this times) requested heavy armored and persistent anti-zeppelin fighter able to operate at night. The aircraft designer Harris Booth from AD (Admirality Air Department) invented one seated biplane fighter armoured by Davis recoilless gun (intended, but never fitted in view of the fragility of the airplane's construction)and in 1915 entered production of two prototypes to the aircraft companies Blackburn and Hewlett/Blondeau. Only one of them was build by the first of the two (another resources mention four prototypes built by the both of the companies, though) and then tested in Chingford, but the tests didn't last very long. All the construction was extremely unstable and all the project was canceled very soon and the prototype(s) scrapped.