New works on the Metropolitan Railway: entrance to the Clerkenwell Tunnel, 1868. This section...is to be used jointly by the Metropolitan, the Great Western, Midland, Great Northern, and London, Chatham, and Dover Companies trains...the Clerkenwell portion...between Farringdon-road and Kings-cross, will become the great central artery for the internal traffic of the whole metropolis, as well as the common link of connection between the great national railways...the Metropolitan Railway Company, with the aid of their chief engineer, Mr. John Fowler...have made extraordinary efforts to prepare for the accommodation, of the greatest number of trains, under so many different managements. One of their principal works during the last twelvemonth has been the widening or doubling of the Clerkenwell section, which has involved the construction of a second tunnel, alongside, the former tunnel, from Kings Cross to Ray-street...in addition to diverting the course of sewers and water-mains and the shifting of gas-tubes, the new line necessitated the pulling down and rebuilding of portions of the old or main-line...The new tunnel, commencing at Kings Cross, runs parallel with the tunnel of the Metropolitan proper, and, like it, emerges at Ray-street. From "Illustrated London News", 1868.