It runs from Bamber Bridge just south of Preston, through major junctions with the M6 and M61 motorways, east past Darwen, Blackburn, Accrington, Burnley, Brierfield, Nelson and ends at Colne.

[2][3][4] This extension was the scene of a standoff between construction security workers and protesters forming part of the environmental direct action movement.

Protesters occupied abandoned buildings in Darwen, parts of Stanworth Woods near Feniscowles and needed to be physically removed.

The opening ceremony took place on the westbound carriageway beneath junction 5 at Guide with a heavy police presence as protesters threatened to bring a halt to the proceedings.

Much of the 1997 extension was relaid shortly after it opened with a new, quieter tarmac because the amount of road noise had been so great that it prevented birds of prey (mainly owls) from foraging effectively.