The eastern tunnel was taken out of railway service in the 1970s but is maintained to ensure the integrity of the ground overhead, and provides road vehicle access to Holloway Bank.

This section of the railway was designed by the engineer Thomas Brassey and was built by Pearce and Smith and John Jay.

The name is taken from Copenhagen Fields, an open space directly above the tunnels, that was once the location of the Ambassador of Denmark's residence in the 17th century.

[2][3] From this site on 21 April 1834 thousands marched in support of The Tolpuddle Martyrs who had been sentenced to transportation to Australia for forming a trade union.

[4] Market Road Gardens, an open space directly above the tunnels, are a present-day surviving remnant of the Fields.