Work No. 2AA—U.K.A railway (883 metres in length) commencing by a junction with the railway (Work No. 2A) at its termination, passing in tunnel north-eastwards beneath the railways (Works Nos. 1C and 2), St. Pancras Basin, the Regent’s Canal and the diverted York Way (Work No. 5Q), then passing north-eastwards and northwards under the railways (Works Nos. 1AA, 1BB and 1DD) to a tunnel portal at a point 40 metres south of the southern side of the viaduct carrying the North London Line over the East Coast Main Line, then continuing under the North London Line on viaduct and terminating by a junction with the Great Northern Suburban Line at the southern portal of the western bore of the Copenhagen Tunnel on that railway;