Construction and opening on the overbridge The Copenhagen Tunnel was the last section of the line into London to have its contract issued. To the north was
Thomas Brassey's contract, and to the south was John Jay's contract for the temporary station at
Maiden Lane. The contract was awarded to the London-based duo Pearce and Smith who started work on 27 March 1849. The name is taken from Copenhagen Fields, which were the gardens of the Danish Ambassador in the 17th century. The fields are notable for being the site of frequent protesting, including against the conviction of the
Tolpuddle Martyrs, with the government forced to release them. Pearce and Smith were the largest buyers of lime by far in 1849, and it is possible that this was used for the Copenhagen Tunnel. The construction of the tunnel attracted great interest from locals who came to watch the bricks being made. The kilns that the bricks were burnt in were coal-fuelled and exposed, which led the bricks to have an unusually red colour but did not affect their efficacy. To save money, Pearce and Smith also sometimes used sawdust rather than sand which was supplied by a
sawmill. They also used a single steam engine to power the mortar mill, lifts in the tunnel shafts, and the sawmill. The original tunnel is now the middle of three parallel bores. A second tunnel to the west was built in 1877 and a third one to the east in 1886. The western bore carried
up and down goods traffic, the central one was used for down passenger traffic and the eastern bore was used for up passenger traffic. Following electrification in the 1970s, the layout was remodelled. This was helped by the fact that King's Cross Goods Yard and
Top Shed had closed, so it was possible to remove the goods lines. The eastern tunnel was taken out of railway service but maintained to ensure the integrity of the ground overhead – it provides road vehicle access to Holloway Bank. The 1955 British comedy film
The Ladykillers is set in the area around King's Cross and St Pancras railway stations and their old goods yards. One of the sets for the house of the protagonist, Mrs Wilberforce, was built perpendicular to the end of Frederica Street, which sat close to the south portal of the Copenhagen Tunnel. Immediately to the south of the set was the spur which carried a track above the tunnel to the goods and coal yard. In one scene from the film the characters dump others' dead bodies over the south portal of the tunnel onto the tracks below. None of Frederica Street, the set, the coal and goods yard, and the spur of track survive today. In January 2024, the Copenhagen Tunnel and the neighbouring Gasworks Tunnel became the first in the country to have new signal-boosting technology fitted inside. This stops devices from losing signal and allows passengers to continue calls while travelling through the tunnels. The upgrade was funded entirely by
London North Eastern Railway. , the operators passing through the Copenhagen Tunnel include
Grand Central,
Great Northern and Thameslink,
Hull Trains, London North Eastern Railway, and
Lumo. == See also ==