Wickham is on the course of a Roman road that linked Calleva Atrebatum (Silchester) with Corinium Dobunnorum (Cirencester).

[1] An open field system of farming prevailed until 1820, when the common lands of Wickham and most of the rest of Welford parish were inclosed.

Later a nave and small chancel were added to form a chapel of ease for Wickham, which in the Middle Ages was a hamlet of Welford.

[1] By the time of the Domesday Book in 1086 the Benedictine Abingdon Abbey seems to have held the parish church at Welford and its chapel at Wickham.

During the reign of Henry I, between 1100 and 1135, St. Swithin's had to provide 40 pounds (18 kg) of candle-wax per year for the altar at Abingdon Abbey.

Benjamin Ferrey greatly enlarged and altered it, adding a tower, spire and remarkable Gothic Revival bay windows.

[2] The Jacobean pulpit from St Swithin's was dismantled and its panels used to make a cupboard in the servants' hall of the house.