In order for this to happen, the existing Thameslink tunnels between Kentish Town and King's Cross Thameslink were closed between 11 September 2004 and 15 May 2005 while the works were carried out.
For at dette kunne lade sig gøre måtte de eksisterende Thameslink-tunneller mellem Kentish Town og King's Cross Thameslink lukkes mellem 11. september 2004 og 15. maj 2005, mens arbejdet blev fuldført.