Early in 1915, in response to the activities of the German forces in mining under the allied positions at the Western Front, companies of the Royal Engineers and the allied forces reluctantly began countermining on a small scale. Specialised Tunnelling Companies were formed for the task and many miners were recruited for the underground work. http://www.users.waitrose.com/~philipclifford/Mines_Rescue_and_World_War_1.htm
Found this ... thought this was interesting ..... I hadn't seen the difference in pay mentioned before !
