The Hertford, Luton and Dunstable Railway was a railway affiliated to the Great Northern Railway. It was formed when the Hertford and Welwyn Junction Railway (opened 1858) merged with the Luton, Dunstable and Welwyn Junction Railway, partly opened in the same year. The merger and change of title took place in 1860. The line joined the Dunstable branch of the London and North Western Railway at Dunstable.
For some time the HL&DR was the only railway at Luton, and the early industry took considerable benefit from it, and later industry was encouraged by it. Even when the competing direct line from Luton to London was opened, the route via Hatfield held its own for some time. The Hertford extremity did not fare so well, and remained rural and relatively undeveloped throughout its life.
Passenger services on the Hatfield to Hertford line ended in 1951; those between Hatfield and Dunstable ended in 1965. Goods traffic did not last much longer. A guided busway was installed on the trackbed between Luton and Dunstable in 2013.