The village was founded in 1278 by the Bishop of Lincoln when, during his visitation to the parish of Aston Clinton granted William de Clinton, lord of that manor, the right to build a chapel on the site of a former hermitage belonging to Missenden Abbey. The original chapel was dedicated to St Leonard of Blakemore.
Following the dissolution of the monasteries the chapel fell into disuse until 1586 when Queen Elizabeth allowed services to be held there once more, for the local woodsmen, because Aston Clinton church was a good hour's walk away, and the long journey stopped them from getting on with their work. The chapel thus operated as a hamlet within Aston Clinton parish.
The chapel is timber framed and is largely of Fifteenth century construction, though some evidence of the earlier chapel remains. Today St Leonards continues to belong to Aston Clinton, though the local population has grown and St Leonards is considered a separate village by local people.