Kedermister Library at St. Mary's Church, Langley Marish, was established by Sir John Kedermister in the early 1600s for the benefit of vicars of Langley Marish. 300 theological books are still housed in the ornately decorated room.

From the 16th century several generations of Kedermisters acted for the Crown as Keepers of Langley Park. In 1607 John Kedermister succeeded his father as Keeper of Langley Park, and was knighted in 1609. Sir John Kedermister was responsible for improving St. Mary's over twenty years. The old bell tower was replaced, 4 almshouses were built and a south aisle was built on to St. Mary's Church, which included a library

The library was stocked with early printed books, mostly published between 1610 and 1637. Mary Kedermister, who survived her husband by 6 years, continued to purchase books after her husband died in 1631. The Missale Romanum, published in 1485, is the oldest book in the current collection. The library's most valuable manuscript, the 11th century illuminated Gospels, was loaned to the British Library in 1932.

The books are conserved and made accessible to the public by the Kedermister Library Trustees, who include two County Councillors, a nominee of the Buckinghamshire Archaeological Society and the Rector of St. Mary's, Langley. More information about the history of Kedermister Library can be found on the web site of The Centre for Buckinghamshire Studies http://www.buckscc.gov.uk/archives.