Watling Street runs for over ten miles from the heart of the West End to the very edge of the capital, nigh straight and essentially roundaboutless. Not only is today's Edgware Road a Roman survivor but it's also probably London's most influential road democracywise. That's because for a full eight miles the roadway marks the precise dividing line between five London boroughs, and indeed seven London constituencies, and all because an army of soldiers once chose to march this way. Let's see how the divide stacks up.
We can ignore Watling Street from Marble Arch to Kilburn because that's all in a single borough. It wasn't before 1965 but then Paddington and Marylebone merged with Westminster and the old boundary disappeared. These days the dividing line starts here.
This is the junction of Maida Vale (the A5) and the somewhat minor Greville Place. Westminster is on the left and Camden on the right. But the Westminster boundary lasts barely 300m before crossing into Brent at Oxford Road, and a heck of a lot of Brent follows. We get all of Kilburn and then all of Cricklewood, which is where the borough of Barnet interrupts on the right-hand side. Three miles of solid boundary continue fractionally past the mega-junction at Staples Corner before finally dissipating here.
This is the bridge where the A5 crosses the river Brent. Here the boundary between Brent and Barnet meanders off, quite literally, following the former course of the river across what's now the Welsh Harp Reservoir. For the next mile both sides of the A5 are in Barnet, just as they were always previously in the borough of Hendon, and Watling Street's peripherality takes a break. It restarts again here.
This is the junction of Edgware Road and Kingsbury Road, just the other side of West Hendon. The borough to the right is still Barnet, and will be for the next five miles, but on the left-hand side Brent has just crept back in. The Brent/Barnet combo carves through Colindale as far as Burnt Oak where the London borough of Harrow takes over, then the Harrow/Barnet divide continues through Edgware and the outer edge of Stanmore. Then it's on up Brockley Hill - Roman settlement on the right, Royal Orthopaedic Hospital on the left - before London comes to an end here.
This is the bridge over the M1 at the Brockley Hill roundabout, just south of Elstree. To the left of the bridge it's still Harrow, to the right it's still Barnet and the roundabout straight ahead is all Hertfordshire. And that's where this amazing boundary run finally comes to an end after three miles through Kilburn/Cricklewood and five miles through Colindale/Edgware. No other London street divides more.
Other very long ancient boundaries Counters Creek: Hammersmith & Fulham v. Kensington & Chelsea (4½ miles) Watling Street: Westminster/Brent/Harrow v. Camden/Barnet (3+5 miles) River Lea: Enfield/Haringey/Hackney/Tower Hamlets v. Waltham Forest/Newham (16 miles) River Thames: Hounslow/Hammersmith & Fulham/Kensington & Chelsea/Westminster/City of London/Tower Hamlets/Newham/Barking & Dagenham/Havering v. Richmond/Wandsworth/Lambeth/Southwark/Lewisham/Greenwich/Bexley (35 miles)
