 In anticipation of the A & B refusing to cooperate , a tentative agreement was reached with the London and North Western Railway , with whom Watkin was on good terms , for the MR to build a route via Chesham to connect to LNWR mainline . This scheme would provide the LNWR with an alternative route into London when necessary , while providing Watkin with his long @-@ sought connection to the north . The land required for an intermediate station near Chalfont St Giles and a line between there and a site outside Chesham was purchased . Agreement was reached with the LNWR that the costs of building the line would be shared equally by the MR and LNWR in return for the LNWR having running rights to Rickmansworth , and an Act of Parliament authorising the extension was obtained in 1885 . 
