The A5201 is an east-west route passing just to the north of the City of London.
The road starts on Clerkenwell Road at the point where the A401 heads up Rosebery Avenue, and then heads east through Clerkenwell until it hits the A501 ring road at a big roundabout at Old Street Station. The name of the road is Old Street once it crosses the A1 Goswell Road.
Old Street Roundabout.
The whole of the A5201 east of the A501 City Road is a primary red route. The first section after the roundabout forms part of the ring road, then that heads along the A1202 Commercial Street while the A5201 continues along Old Street until it goes under the East London Line and meets the A10, still apparently primary. The A5201 ends here, with the A1208 Hackney Road continuing on the far side of the traffic lights.
There are no signs indicating the number of this road during its primary section. As it used to be part of a one-way gyratory system it may well have all been the A1202 previously. All the maps show it as the A5201, however, including the 1923 MoT map.