At Faringdon, its traditional route over Folly Hill and down through the market place has been blocked by the more recent development of the A420 and the road has been diverted to the south.

The Birdlip bypass, opened in 1988, avoided a steep (16%) gradient as the road descended the Cotswold Edge escarpment to Brockworth.

[3] The road runs north-west from Streatley at its junction with the A329 (between Reading and Wallingford) then turns west to Wantage, over the picturesque[4] Berkshire Downs.

This is a bottleneck at peak times, and plans for a dual-carriageway section here were included in a roads expansion programme pledged during the government's 2014 Autumn Statement for delivery during the following 5–8 years.

It crosses the M50 Ross Spur motorway at junction 2, then meets the Ledbury bypass, where the road noticeably widens out, and has many large roundabouts.

From Ledbury it goes west, overlapping the A438, then at a set of traffic lights known as the Trumpet crossroads, the A417 goes north-west along a more high-hedged, narrow road.