|To:||Royal Wootton Bassett (SU074836)|
|Length:||4.9 miles (7.9 km)|
|Meets:||B4040, A429, B4696, A3102|
|Route outline (key)|
The B4042 is a short rural B-road in north Wiltshire that connects the town of Malmesbury to Royal Wootton Bassett.
The road starts on the one-way system in the centre of Malmesbury, where it meets the B4040. It heads southeast along the pre-bypass route of the A429 and crosses the River Avon before meeting the A429 Malmesbury bypass at a roundabout. The Avon is soon crossed again at Cow Bridge. The road then goes across rural Wiltshire, passing past farms and scattered houses until it reaches the village of Brinkworth, claimed as the "Longest Village in England" on roadsigns. The road reduces to 50mph then to 30mph whilst it goes through the core of the village.
Once through, the road goes through Callow Hill then meets the B4696, after which the B4042 passes under the M4 and then terminates at Royal Wootton Bassett on a roundabout at the A3102 (formerly A420).