Haddenham derives its name from 'Haeda's homestead'. In 673 it was part of Queen Etheldreda's marriage endowment. A church has stood on the hill since then as Ovin, Etheldreda's minister and steward, had close connections with the village.

The present building is late thirteenth and fourteenth century, but with major restoration dating to 1876 by R R Rowe.

The structure is rubblestone and limestone ashlar and dressed limestone with leaded roofs and end parapets with nineteenth century gable crosses.

The tower once supported a lofty steeple, however, during a refurbishment in the latter half of the nineteenth century, the steeple was removed for safety reasons and the then treasurer, reputedly, fled to the United States with the money to rebuild it. Holy Trinity remains to this day without a steeple.

In 1763 a stone bearing the Latin inscription: 'Grant O God to Ovin Thy Light and Rest. Amen' was found being used as a horse mount outside a public house near the church. the stone, known as 'Ovin's Cross', was taken to Ely Cathedral, but a replica can be seen on the north west corner of the churchyard. It is the only piece of stonework, of Saxon origin, in Ely Cathedral.

Thomas Arundal, Archbishop of Canterbury between the years 1396 and 1414, is buried inside Holy Trinity. His tomb can be seen beneath the tower.