The Northampton to Market Harborough line opened in 1859 and had tunnels at Oxendon and nearby at Kelmarsh.
The original tunnel was single-track, and when the line was doubled a second single-track tunnel was built.
Due to the small bore, the tunnels were known as "the rat-holes" by train drivers.
The former "up" line tunnel at Oxendon is open as part of the Brampton Valley Way, a linear park which runs from Boughton level crossing on the outskirts of Northampton to Little Bowden near Market Harborough, on the former railway trackbed.
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