|Location Map ( geo)|
|Distance:||14.3 miles (23 km)|
|Met (1956):||A350, A342, A4, A420|
|Now part of:||A3102|
|Route outline (key)|
In the 1960s the section from Melksham to the A342 was upgraded to Class I status, becoming the imaginatively named A3102; the section immediately west of the A342 was rerouted to join it further south.
After the M4 was constructed across northern Wiltshire, the centre section of the A420 was downgraded to be the B4069, with the remainder of the B3102 being upgraded to the A3102 at around the same time. The new A-road also took on the route of the former A420 into Swindon.