It looks as though it must have been designed that way from the start, but it actually came together over the centuries more or less by accident.The nave was built first, in Norman times, as shown by a small window on the north wall.
In about 1200, the chancel was added (or rebuilt) and a tower constructed to the north, with an arch into the nave. The chancel and tower arches are typical of the early 13th century, with a plain chamfer on the edges rather than complex moulding. The tower arch is much deeper than the chancel arch, indicating the heavier load it had to support.
A transept was added on the south in the later 13th century, shown by the more sophisticated concave chamfers on the arch. Both chancel and transept have a piscina, a stone basin in an arched recess used for washing communion vessels, showing that the transept would have had its own altar.
At some point the north tower was demolished, possibly when the existing west tower was built in the 16th century in the Perpendicular style. At this point the base of the tower became a transept and the accidental cruciform plan of the church was complete. As with many churches, the design evolved rather than being created by an architect.
As an appendix to last month's article on monuments to knights in armour, Thakeham contains the alabaster tomb chest of William Apsley who died in 1527. William is depicted in full late medieval armoural in lines deeply incised in the slab and filled with pitch, a type of decoration unique in Sussex.
One of the main things visitors remember about Thakeham is the slightly perilous climb up the stone path to the church, and the fabulous view from the churchyard.