This article is about the original B155 from East Barnet to Potters Bar. For the current B155 from West Green to the Roundway, see B155. For the former B155 along Westbury Avenue, Wood Green, see B155 (Westbury Avenue).
The B155 was originally allocated to the road between East Barnet and Potters Bar across Enfield Chase in North London. By 1926, it had been upgraded to a northern extension of the A111.
The road started at what is now the Cockfosters Roundabout on the A110. Here the A111 headed south and the B155 north. In 1922 this road was completely rural - it ran across Enfield Chase, passing even fewer buildings than it does now. After a couple of miles it ended to the south of Potters Bar on the A1005.
When the A111 took over the B155 it was also extended north to Potters Bar and the A1000. Later still the M25 was built through the area and its J24 has destroyed the original northern end of the B155.