The Herford East branch line is part of a collection of London consumer routes called the Lea Valley lines that run along which river?
Hertford East branch line: The Hertford East branch line is a railway line in Hertfordshire in the United Kingdom, running between Hertford and Broxbourne . Lea Valley lines: The Lea Valley lines are two commuter lines and two branches in North East London, so named because they run along the Lower Lea Valley of the River Lea.
i don't know