When the
London and Birmingham Railway (L&BR) was constructed in the 1830s, Northampton was by-passed, with the line running on high ground to the west via
Kilsby Tunnel. Traditionally, this was said to have been because wealthy Northampton landowners objected to having a railway run through their land to reach the town. However, an alternative view is that Northampton was by-passed because the
gradients would have been too steep for the early locomotives of the 1830s to easily cope with.
Robert Stephenson the engineer of the London and Birmingham Railway was determined to avoid gradients steeper than 1:330 (that is one
foot of rising or falling gradient for every 330 feet of distance). As Northampton is located in the
Nene Valley, lower than
Blisworth, the closest point the L&BR came, connecting the town would have required gradients significantly steeper than this. This meant however that Northampton, despite being a large town, did not have direct rail links to London. A branch from the main line was built to Northampton in the early 1840s: the
Northampton and Peterborough Railway, from
Blisworth, which gave the town indirect rail links to London and Birmingham. Shortly after the completion of the loop line, the southern approach to Rugby station was remodelled, with a new
flying junction built near
Hillmorton, which allowed trains from the loop line to run into Rugby station without conflicting with trains on the fast lines. ==Services and operations==