The River Allen (Cornish: Dowr Lehen, meaning slate river) in north Cornwall is one of two rivers in Cornwall which share this name. In this case the name is the result of a mistake made in 1888 by Ordnance Survey, replacing the name Layne with Allen which is the old name for the lower reaches of the Camel.[1] The other River Allen runs through Truro.
The River Allen is a major tributary of the River Camel. It springs northeast of Camelford and flows south-southwest through the Allen Valley passing St Teath and St Kew Highway to join the Camel near Sladesbridge.[2][3]