It runs from Streatley at its junction with the A329 (between Reading and Wallingford) to Wantage, over the picturesque Berkshire Downs. In Wantage, it negotiates the market place (around King Alfred's statue and thence to Faringdon, via Stanford in the Vale. It leads on to Lechlade, where it crosses the River Thames. It then runs past the Cotswold Water Park, through Fairford to Cirencester and thence to Gloucester.