Plans of signal boxes from the Doncaster District showing alterations to withstand attack. File list includes signal boxes at: Bardney, Barnetby, Bentley, Brocklesby, Conisborough, Balby Junction, Bessecar Junction, Black Carr Junction, Bridge Junction, Childers Drain, Decoy, Doncaster, Gainsborough Trent Junction, Goxhill, Greetwell Junction, Grimsby, Hexthorpe Junction, Immingham, Keadby, Kirk Sandall Junction, Lincoln, Louth, New Holland, Newark, Retford, Saxilby, Scunthorpe, Stainforth and Washingborough.