The B140 is a short road in the East End of London. It was originally unclassified but gained its number in the second quarter of the 20th century.
The road starts at a double mini-roundabout on the B121 next to Stepney Green Maths, Science and Computing College. From here it heads east along Ben Jonson Road and soon crosses a bridge over the Regents Canal. On the far side it bears right to cross the southern side of Mile End Park. There's then a narrow bridge under the LTS railway line and a single set of traffic lights serving two unclassified roads off to the right before we cross the A1205 at another set of lights.
Passing the modern St Paul's Church we continue east along St Paul's Way, which briefly becomes a shared space as it passes a row of shops. The road now bears to the left to become Devons Road and presently we cross a roundabout and then a mini-roundabout to go over the Docklands Light Railway by Devons Road station. On the far side we reach traffic lights, where Devons Road – and with it, the B140 – TOTSOs left. (The road ahead, Devas Street, leads to a grade-separated junction with the A12 Blackwall Tunnel Northern Approach.)
After passing beneath the District Line by a low bridge (3.6 m), the B140 bears right into Bruce Road, which shortly ends at a T-junction where we turn left into St Leonard's Street. Our route merges into the eastern end of Bromley High Street before becoming one-way and joining the northbound offslip of the A12 at its junction with the A11.