18" Railway Howitzer HMG 'Boche Buster' siting outside the southern portal of Bourne Park Tunnel on the Elham Valley Railway during operational manoeuvres, Bishopsbourne, Kent, March 21, 1941. Deployed in Kent during 1941 alongside a number of other Railway Guns, the Howitzer did not have the necessary range for cross-Channel firing and was intended as a Costal Defence gun in the event of a German invasion.