After the junction, the road heads out of town through Speenhamland along Western Avenue and Bath Road to the junction with the A34 Newbury bypass.
 The Newbury bypass was opened, after some controversy, on 17 November 1998, at a cost of £104 million.
The route heads over undulating countryside in a fairly straight westward direction towards Hungerford parallel to the Kennet and Avon Canal and crossing the River Kennet on the outskirts of the town at the same time as intersecting with the A338.
 The route does not enter the town centre, but continues westward to the northern side of town on its way to Marlborough via the village of Froxfield and the northern edge of Savernake Forest.

On entering the outskirts of Marlborough the road follows London Road.
Crossing the River Kennet again it briefly shares the highway with the A346 which connects northwards to Swindon.
It splits again at a roundabout along New Road and Oxford Street into the town centre on the High Street.
The High Street is a traditional main thoroughfare for an English market town, in that it is wide, with space for market stalls on either side and in the middle, though these spaces are usually marked for car parking.

Until the late 1980s most of this section, and some of the following Wiltshire section, was configured as three lanes, with the central lane available for overtaking traffic in either direction.
 This is no longer considered safe so the road now has one wider-than-normal lane in each direction, with ghost islands at junctions to discourage overtaking at these points.
After the junction, the road heads out of town through Speenhamland along Western Avenue and Bath Road to the junction with the A34 Newbury bypass.  The Newbury bypass was opened, after some controversy, on 17 November 1998, at a cost of £104 million. The route heads over undulating countryside in a fairly straight westward direction towards Hungerford parallel to the Kennet and Avon Canal and crossing the River Kennet on the outskirts of the town at the same time as intersecting with the A338.  The route does not enter the town centre, but continues westward to the northern side of town on its way to Marlborough via the village of Froxfield and the northern edge of Savernake Forest.
On entering the outskirts of Marlborough the road follows London Road. Crossing the River Kennet again it briefly shares the highway with the A346 which connects northwards to Swindon. It splits again at a roundabout along New Road and Oxford Street into the town centre on the High Street. The High Street is a traditional main thoroughfare for an English market town, in that it is wide, with space for market stalls on either side and in the middle, though these spaces are usually marked for car parking.
Until the late 1980s most of this section, and some of the following Wiltshire section, was configured as three lanes, with the central lane available for overtaking traffic in either direction.  This is no longer considered safe so the road now has one wider-than-normal lane in each direction, with ghost islands at junctions to discourage overtaking at these points.
A4 road (England)