The College Burn and Bowmont Water, both flowing out of the Cheviot Hills, meet near Kirknewton to form the River Glen.

The Glen flows past the small settlements of Yeavering, Lanton, Coupland, Akeld and Ewart, before joining the Till.

Iron Age hillforts on peaks to the south of the river overlook the Anglo-Saxon settlement and palace site at Yeavering, where St. Paulinus baptised new converts and, according to Bede, "washed them with the water of absolution in the river Glen, which is close by" (Tomlinson, 1888, p. 504).

A reference to a similarly named river in Historia Brittonum by the Welsh author Nennius, some (Ekwal, 1928; Hunt, 2005) have hypothesized that the legendary British warrior Arthur began his campaign against Anglo-Saxon invaders near the confluence of the Glen and Till: Between 1966 and 2010 the flow of the Glen, was measured in its lower reaches at a weir near Kirknewton.

The 44 year record shows that the catchment of 200 square kilometres (77 sq mi) to the gauging station yielded an average flow of 2.93 cubic metres per second (103 cu ft/s).