mond o ▁De ▁Am ic is ▁( 1 8 4 6 – 1 9 0 8 ) ▁gave ▁a ▁description ▁of ▁a ▁passage ▁through ▁the ▁sub way ▁in ▁his ▁J ott ings ▁about ▁London : ▁ ▁In ▁ 1 8 9 4 ▁the ▁to ll - free ▁Tower ▁Bridge ▁opened ▁a ▁few ▁hundred ▁yards ▁down river , ▁causing ▁a ▁drop ▁in ▁the ▁sub way ' s ▁income . ▁In ▁ 1 8 9 7 , ▁Parliament ▁passed ▁an ▁act ▁author ising ▁the ▁sale ▁of ▁the ▁tunnel ▁to ▁the ▁London ▁H yd ra ul ic ▁Power ▁Company ▁( L HP C ) ▁for ▁£ 3 , 0 0 0 , ▁and ▁the ▁sub way ▁closed ▁to ▁ped est rian ▁traffic ▁in ▁ 1 8 9 8 . ▁ ▁Util ity ▁tunnel ▁ ▁After ▁its ▁closure , ▁the ▁tunnel ▁gained ▁a ▁new ▁purpose ▁as ▁a ▁route ▁for ▁hyd ra ul ic ▁power ▁main s ▁operated ▁by ▁the ▁L HP C ▁and ▁for ▁water ▁main s . ▁It ▁was ▁dam aged ▁during ▁the ▁Second ▁World ▁War ▁when ▁a ▁German ▁bomb ▁fell ▁in ▁the ▁river ▁near ▁Tower ▁Pier ▁in ▁December ▁ 1 9 4 0 , ▁and ▁expl oded ▁on ▁the ▁river ▁bed ▁very ▁close ▁to ▁the ▁tunnel ' s ▁roof . ▁The ▁shock ▁of ▁the ▁bl ast ▁com pressed ▁the ▁tunnel ▁radial ly , ▁reducing ▁its ▁diameter ▁to ▁▁ ▁at ▁the ▁point ▁of ▁impact , ▁but ▁the ▁tunnel ' s ▁l ining ▁was ▁not ▁pen etr ated . ▁During ▁the ▁course ▁of ▁repair ▁work , ▁it