The Church is built of roughly dressed sarsens which it is believed were found throughout the local area with many rejects still lying nearby and even in the stream that flows close by. A close inspection of the north transept shows that its stones are more roughly dressed than those of the rest of the building, most obviously in its east wall. The exception to the use of sarsens is the tower.
The tower is dated about 1450 and may have replaced a smaller one. The faced blocks of Corallion stone provide a contrast to the fabric of the rest of the church. The construction of the tower may have been by Richard Beauchamp, the Bishop of Salisbury from 1450 to 1481.
No structural work earlier than the fourteenth century can be seen in the nave although the font is probably early thirteenth century. The former diocesan architect Mr C.E. Ponting provides a description of the nave.
"The south wall of the nave appears to have been a great deal altered, but the part eastward of the porch without plinth is probably earlier than the rest, and the three-light window inserted here is of a very late debased type. The four-light pointed window westward of the south porch is a beautiful specimen of the work of the middle fifteenth century. One wonders why so large a window, inserted so near to the end, was put; this part of the wall appears to have been rebuilt at this time, for it has a plinth and is the only piece, excepting the tower, which possesses this feature - the wall is also, unlike the rest, faced with freestone."
The south door, late Perpendicular, has the initials GA with 1611 carved above.
The north aisle has an arcade of three pointed arches without capitals and a small pointed Perpendicular window. The north door has a four-centred arch with carved paterae of ball-flower set in four leaves (although the one in the apex has been cleverly arranged with five!) connected by continuous stems, all set in a hollow mould. A nicely moulded label sits over the door with one head terminal and a plain corbel, the purpose of which is unclear despite appearing to be of the same age.
The chancel is of mid-thirteeth century date but has undergone two restorations. In 1610 the roof was lowered cutting off the tops of the side windows. These tops were restored when the roof was raised again in 1857, the east window (an excellent copy of a window of the Decorated period) being inserted at this time. The window glass dates, however, from 1926.
The communion rails were formed from the tops of the old high pews during the restoration of 1857. An elegant piscina is to be found in the chancel and is similar to the one in the north transept.
An external inspection of the church reveals that the north transept is older than the rest of the church and may be part of a smaller original church. A fine fourteenth century window can be found here beneath which is a recessed tomb from a century later. This niche has a, probably contemporary, arch supporting four image stands. Aubrey wrote
"In the north aisle under the window, which is of the fashion of Edward III is an old nich, within which on a stone is the lineary figure of a man and his wife, of whose name here is no tradicion".
In the burial register a note dated 11 May 1842 reads
In the north aisle of Winterbourne Church was discovered a stone coffin with two figures carved on the lid supposed to be the founder and his wife. The coffin lay under a canopy concealed by a mass of brick and mortar, which has been there more than a century. On being opened it was found to contain one skull and the bones of more than one body. It had been opened before and the lid was broken and otherwise mutilated".
Taking both these accounts into consideration the story of the coffin would appear to be as follows. When seen by Aubrey the coffin was below floor level with the lid flush to the surface (not an uncommon arrangement). The floor level was later raised covering the lid and coffin with rubble which was later removed thus revealing the coffin once more. Exposed stone coffins are rarely moved, except during major reconstructions, and the above would suggest only minor vertical movements - maybe the coffin still lies beneath!
The figures can be seen in a dexter handclasp which denotes an heiress and they probably represent Hugh le Despenser and Alivia daughter and heiress of Sir Philip Bassett of Wycombe. Alivia held Winterbourne Bassett for life only.
Memorials to the Baskerville family who owned the Richardson estate for several centuries can also be found in the north transept. The Baskervilles came from the borders of Wales and were settled from an early time at Eardisley in Herefordshire. The two fine wall memorials are to Margaret Baskerville, daughter of John Glanville of Broad Hinton, who died in 1696 and to Mary Baskerville, daughter of Richard Jones of Hanham (Gloucestershire), who died in 1724. Aubrey recorded another monument to Simon Baskerville, son of Sir Walter Baskerville of Eardisley, who married the widow of William Hutchins of Richardson in the middle of the sixteenth century. Unfortunately this monument is no longer present and may have provided the clue to the Baskerville connection with Winterbourne Bassett. Altogether eight generations of Baskervilles owned estates in Winterbourne Bassett, Wanborough and Rockley, and when the family died out in 1817 the lands passed back to the main branch of the family.